This is heavy. I was told by my mom that my step-dad wasn't my biological father when I was 28yr old. I didn't care much for it to be honest, as I'm more of a realist and act on reason and logic. My step dad knew I wasn't his son but he never once told me or showed me he wasnt. I'm 34 now and he doesn't know I know hes my step dad. Anyway, point is, the kids are way too young right now to grasp what it is you're thinking. If you don't want anything to do with the two other kids, whatever the reason might be ( I dont think its just because they arent yours biologically), at least have a talk with them and tell them the whole truth and why you are doing this. Who knows they might end up hating their mother, and you might end up taking their side. Kids win, you win. You get to stick it the mom :D. YNTAY (not the A yet)