Op after reading the rest of the thread I'll tell you how we do things. I know I'll get flamed b/c I have before but I want to say one thing to that first. BITE ME!
This is how we handle christmas and such holidays--- I buy more for my kids then for my step sons as this is the only christmas that my kids get and always have. I give my kids their gifts from me while my step sons get their gifts from their mom. I don't see anything wrong with that as all kids are getting gifts from THEIR mothers!! I get my kids a main gift that is more then my steps kids and then after that it is all fair. Soooo while step sons are getting their gifts from their mom my kids are opening the gift from me. So while the step kids are here they get the same as my kids. Does that make since? I have never let it be in their face that I spend more on my kids b/c they are not here while I give my kids their gifts. Now it would be different if my kids seen their dad or had any contact with that side of their family but they don't. Their dad and his family is MIA and always has been I don't even get Child Support!
This makes perfect sense to me and is how we handle it.