i'm not into incest stuff, but it would be pretty easy to explain that. it's not rare for kids to choose their preferred parent in a divorce, or for parents to force their kids to follow them. also Annie could be MC's half sister, and their dad could just have had a lover in the UK who he impregnated around the same time as MC was conceived. Nancy found out. divorce. Dad moves out to the UK with his lover and son, as he doesn't care about his daughters, or the daughters preferred their mother and the son didn't really choose. but Nancy, Penny and Dalia accepting Annie in their home would be a different story. Nancy could be understanding that it's not Annie's fault and she is innocent, and MC cares about his half sister enough that Nancy wants to make him happy and have her in her home too.