The singer, who replaced founding member Keisha Buchanan in September, admitted that she has grown close to both Berrabah and Heidi Range since joining the group.
"I get on so well with the girls already," Ewen told the Daily Star.
"I'm going to Thailand in January with Amelle and I even stayed at Heidi's mum's house in Liverpool last week."
Ewen recently revealed that 2009 has been the best year of her life so far.
Sugababes release new album Sweet 7 in March.