As previously reported, plans to send the family to Spain for a dramatic new plot had to be scrapped due to cutbacks at the BBC.
Now the clan will travel to Weymouth for the shock script, which will see veteran actor Larry Lamb start his role as Archie Mitchell. The character is set to "blow the family apart".
An insider told the Daily Star Sunday: "The story works just as well in Weymouth. But there are some concerns about the British weather. It's so unpredictable and could cause a few problems for filming outside."
The source added: "They're having to hire extra security to make sure none of the Weymouth locals get a glimpse. It absolutely mustn't be leaked."
The episodes will air in the summer.