The Eurovision star replaced the last remaining original member of the girl group in September 2009. The trio, which also includes Heidi Range and Amelle Berrabah, met Buchanan for the first time since her exit during the summer.
"The Wireless Festival was the first and last time I've seen her since she left," Berrabah told Star magazine. "A couple of times I've been in the same place as her but not seen her."
Revealing her own separate encounter, Ewen said: "I saw her at a wedding the other day and it was really nice to have a conversation with her. I have no issue with Keisha as I wasn't in the band at the time. I did nothing to her and she did nothing to me.
"Everyone seems to want there to be tension between us, but she said she was happy for me and that she hoped we'd do well. And vice versa."
Bandmate Range concluded: "Hopefully now people can leave it. It's boring!"
Sugababes last week announced that their new single 'Freedom' is being released as a free download via Amazon.
> Sugababes: 'New album showcases our personalities'
Watch the Sugababes 'Freedom' video below: