As our interview with Mickey Starke revealed earlier in the week, the kids' mother soon turns up out of the blue to stir the situation.
Digital Spy caught up with Jonathan Dixon and Emma Edmondson - twins Darryl and Mel - to chat about what it was like joining the show, what's to come for their characters and family and what it'll be like coping with their new-found fame.
Is Coronation Street your first TV role?
JD: "No, I actually left Grange Hill a couple of months ago. I was in that for five years as the bully. I went into it when it moved to Mersey Television from up London, and I loved it. It was great - learnt a lot, played the bully there. I was 12 then, 18 now."
Did you get stick at school for playing the bully?
JD: "Everyone knows what I'm like - the complete opposite to that, really. But they're always joking - 'leave him alone' and that."
Will you be bringing your bullying ways to Weatherfield?
JD: "The complete opposite. Darryl's great, he's a likeable character, he likes taking the mick out of everyone - especially his twin sister Mel. He just lazes about all day, to be honest."
He's going to have a good friend in David, do you think?
JD: "Maybe. He goes to college - he's supposed to go to college, but he doesn't like turning in."
Has he got a girlfriend?
JD: "He hasn't, no. I get that question a lot. I don't know who he's going to have his eye on in Weatherfield, but I'm sure there'll be a few, I bet he'll have a few. If he gets knocked down by one, he'll move on..."
Is he quite confident?
JD: "He likes his women, I could see him trying it on with quite a few people."
So you won't have to wait as long as Jack Shepherd for your first kiss, then?
JD: "He keeps saying to me, 'you'd best not get a girlfriend before I do'."
Did you know anybody in the cast before you joined?
JD: "I did. I knew Jack, we've been best friends since nursery. Literally, since age of three. He lives in Pudsey and we've been friends since then, we went to primary school together as well. It's really strange that we're working together on this. We went to drama school together, at the same time, at Stage 84 in Bradford. He gave me the overall lowdown, shall we say."
Has your character got any dark secrets?
JD: "I don't think he's really that snidey and dark. Just your classic teenage lazy boy. He gets on with all the family, much as they all give him grief - as they do when you're a teenager, you get a lot of hassle. He's mainly close to Mel, his twin sister, they're very close, as much as they do get down each others' necks, they are the closest in the family."
How did you get the part?
JD: "I just got a phone call from my agent, from Stage 84. I had left about a year ago, but she was still my agent. She gave me a call and said 'you've got an audition for Coronation Street'. It just went from there, and after about four or five callbacks I thought 'this is still not going to happen' until it got down to the last two. It was one of my best mates who I was up against."
Did you talk to Jack [Shepherd] about it?
JD: "He was on holiday in the Caribbean - I phoned him up and was like 'Jack, I'm down to the last two, you back from your holiday' and he was like 'no' and I was like 'er, get off my phone, it's like four quid a minute!' So I spoke to him - he got back just before my last audition. I met him before and had a drink, told him how terrified I was of going in."
What was your first day like?
JD: "It was amazing. You come in, you are very scared, and I didn't know what to expect - but everyone was so friendly and nice. You were thinking you were going to be interested in everyone, but they were interested in you, which was fantastic. You thought you were going to be a little minor. It was absolutely great - it was like a little family with cast and crew, everyone just gets on so well, and it's strange how everyone just fits together."
Who was your first scene with?
JD: "My first scene was with the family, and with Helen Worth (Gail), which was great as well because I'd obviously been watching everyone on screen all those years, and finally it was like 'go'. It was fantastic."
How did you get Grange Hill at such a young age?
JD: "I think I joined my drama school at about nine. I went to an open audition for a Birdseye advert, and I ended getting down to the last 10 - and I thought 'ooh, close'. So I ended up joining this drama school, and I did plays and stuff like that. Me and Jack have done a few plays together as well. Ultimately I got this audition for Grange Hill, and then it was callback after callback after callback, and eventually - I couldn't believe it - but I got the part. I've been in that for five years."
Do any of the rest of your family act?
JD: "My brother's a singer, he's got an up and coming band called The Weekends. I might be biased saying that they're exceptionally good - they're looking to get signed. They're indie music, they play in Manchester. They write all their own music and they don't do covers. They've played Leeds, Liverpool, all over. In local papers now and again. They are actually fantastic.
If there's one Corrie storyline from the past you'd love Darryl to be in, what would it be?
JD: "I've always said I thought the greatest thing that happened to Coronation Street was Richard Hillman. For definite. It was something that drew people who didn't watch it that often into it. Brian Capron I think is an absolutely fantastic character. I don't think I'd get a buzz out of putting a shotgun through someone, but I would love to be involved in a storyline like that - I said to Jack how lucky he was to be involved in such an absolutely amazing storyline. It was unbelievable where it went from. I thought Brian Capron did amazing things for the Street. Any cast member in that who can achieve something he did is fantastic."
How do you think you'll cope with female attention?
JD: "I already have a girlfriend, I've been with her for a year now. Hanging about with Jack outside work, going for meals and stuff with my girlfriend and his girlfriend - they get on really well, so she's given her the inside 'watch out' talk. She's just really happy for me. It's great."
Where did you meet her?
JD: "I met her at college. She's doing performing arts with me, she's in a play called 'Junk' and her name's Tania Carter. It's at my college in Halifax, it's had a theatre built onto it. I'm going to go and see that tonight - Calderdale College. Brand new theatre, absolutely great."
So, Emma, what's your character like?
EE: "Mel is definitely a Morton in that she's brash and gobby, but out of the whole clan she's the most sensible. Definitely more sensible than Darryl. They're very close, but very different - I think Darryl brings out a bad side of Mel, the naughty side, but apart from that she's got her head screwed on. I think she's likeable, they're all likeable, they'll go down well. She's working in the kebab shop helping Daddy out."
Does she have a boyfriend?
EE: "She doesn't, no."
Could she end up with David?
EE: "She might be a bit old for David, because he's only 16! I don't know about any love interest yet, but it would be nice."
The next Karen McDonald?
EE: "It'd be nice, but she's not that brash! The whole family are quite brash - I think that's going to be a running theme throughout the Mortons. Yeah, I'd like to be that cocky."
Where are you from originally?
EE: "Rochdale. I'm from Greater Manchester, so it's a programme my whole family grew up with. It's nice."
Have you done much acting before?
EE: "I'm a relative newcomer, really, so this is the first big thing I've done. This is my big break, really, so very excited. I'm 22."
What did your parents say?
EE: "They were absolutely over the moon. I said earlier that we used to sit down, my grandparents, aunt and uncle - we grew up with this programme. For my mum, I don't think her feet have touched the ground, I think she's happier than me."
How does your character get on with her siblings?
EE: "I think although she has the closest relationship with Darryl, they fight a bit, she has a calmer relationship with everybody else. With her being the sensible one in the family, she has a good relationship with all of them. I think we're all Daddy's girls in a way, to be honest.
How did you feel finding out that Sinbad was going to be your dad?
EE: "Having Michael Starke - he's obviously quite a name already, so hopefully that'll make the family even more interesting to the viewers. He's such a laugh. I was a massive Brookside fan, I keep thinking I'm going to call him Sinbad."
Have you got a boyfriend?
EE: "I'm a single girl. I think I've got enough on my plate at the moment, to be honest."
How did you get the part?
EE: "Pretty much like Jonny, to be honest. Before Christmas I got a call saying I had an audition for Coronation Street, and I've never auditioned at Corrie before. I thought okay, I won't get it, it's Coronation Street. I just kept going back, and Jonny and I kept meeting each other at each audition - they auditioned for the twins together. We kept seeing each other and were like 'back again?' It just seemed too surreal to think I would get the part. You just don't want to let yourself hope."
JD: "It's actually really funny - they didn't put us together in the auditions till the very last round."
Was it a bit like being on the X Factor?
JD: "The last one was a screentest, and there were two boys and three girls, and we'd never been put together in any of the auditions before. Every boy went with every girl - and they were like 'oh, can you two do together?' We did it together. It was quite lucky, really."
EE: "We kept saying to each other 'why haven't they put us together, cos we look the same'! It's weird. Frightening."
If you could be in any storyline from the past, what would you pick?
EE: "The Karen thing you were saying before, I used to love the Karen-Tracey hatred. Really feisty, bitchiness. I'd love to be in that kind of storyline."
Who are Mel's role models?
EE: "I think that she's quite cool, she's only 18 so she's quite fashion-conscious. I wouldn't say Kelly Osbourne, maybe like Charlotte Church. She's a little bit rebellious, so I think she'd like the cheekiness of Charlotte. She might be a bit of a role model for her."
Why are they living with their dad and not their mum?
EE: "I think our mum's ditched us.'
What's does Mel's future look like?
EE: "I think she would like to have a career. I don't think she's arrogant, she's quite intelligent, so she wants to have an actual career - so as much as she's family oriented and wants to help her dad out, she wants to have her own life. Not forever, as much as she'll help. I don't think she quite knows what she wants to do, but she has her ideas. You can always be a hairdresser on Corrie - but she'd like to use her brain a bit more than working in the kebab shop forever.
What acting have you done before?
EE: "I haven't done much, to be honest, just little bits, nothing that you would really recognise me from. This is my big deal. I did The Street, I once did a Crimewatch reconstruction! I was a rape victim, it was quite a sad story to be honest. I have done something with Crazy Kids when I was younger - I think it's part of growing up in Rochdale, you have to perform. I used to do some dance shows at school when I was very young. Very embarrassing."
How do both of you feel about the attention you're going to get?
JD: "We haven't thought about it, have we?"
EE: "Very naive."
And Jonny, you spend time with Jack - what's that like for him?
JD: "It is bad. You don't really think it's going to get to certain points, and it really does. I don't think Jack can walk down the street without [someone approaching him]."
What did Jack say to you when he found out he got to kiss Kate?
JD: "He told me on the day of my last audition, 'I've got my first kissing scene, I was so nervous'. To be fair, it must be really daunting, specially when there's such an age gap - that'd be well strange. It was his first kissing scene. I'm terrified if I ever get one. You've got 40 crew members going 'go on'. It's quite worrying but he did - I won't say he enjoyed it..."
So Darryl's staying on the sofa where the murder was, then?
JD: "He's not bothered. It doesn't faze him at all. He's not bothered about anything, really. It's quite hard to get to him, apart from when it comes to Mel. He's quite funny in that respect. He isn't a fan of the boys. That's another sign of us being very close twins."
Thanks for chatting, Jonathan and Emma!
Click here to read our interview with father of the family, Michael Starke and here to read our interview with eldest daughter, Jodie, played by Samantha Seager.
Your next clue can be found in a review of a gig by the former frontman of The Smiths