Hmm sounds very familiar to my situation!! I cannot stand my step dad - he treats my mum like utter crap, is the biggest A-hole around and so so SO selfish and immature.

However - my kids don't see their other poppy (my dad) cos he lives in Tassie, so I just sorta suck up my feelings for them ya know? DS is at an age that he will say hello poppy and goodbye poppy - but doesn't have anything to do with him other than that. As soon as we turn up - my step dad is out the door as quick as his legs can carry him... lol... I think he doesn't like me cos when I was younger I yelled at him and got into a huge screaming match with him and told him to stop being such a c*** to my mother... LOL...

So I think what I am getting at - he may not stay in the room long enough for you to be worried about it. Otherwise, I'd worry when the time comes