Could see Pat figuring it out and blackmailing Shona, forcing her to revert to stealing. His comeuppance shouldn't be too far away though.
Can see David eventually falling for Shona, Shona trying to fight it and Gail taking some of the flack for keeping quiet about it. Shona must have been made the same age as Kylie and similar to her in some respects for a reason.
I had thought she'd be Kylie's half sister on her father's side, but in hindsight there'd have been no story then. Moving on to a partner or spouse's sibling seems commonplace in soapland. She was never going to be Kylie's mother - she's dead and Becky went to the funeral, aside from the age thing.