Re: Preparing Older Siblings
I have an almost 5 year old SD and my 4 year old DD. We also have SD 50% of the time. I think our situations are somewhat similar. To prepare our girls for the new arrival we've just done little things here and there. We have a couple of books about being an older sibling and bringing home a new baby that we read to them. We have "Big Sister" shirts for them to wear. We plan to get them each a special gift when their baby sister is born. I've let them pick things out at the store for their sister. I just try to make them feel involved in the whole process. I'm really not worried about how either of our kids will adjust. DD is very, very excited about the baby. My SD's mom actually had a baby last year, who just turned a year old. She has already sort of been through this before and it isn't as big of a deal to her.
As far as problems with your DSS's mom, I hate to say it but there just isn't a lot you can do about that. All you can do is make sure that he has a positive environment when he's in your home. When he comes to you and tells you that mom told him something negative, reassure him that it isn't going to be an issue and everything is going to be fine. My SD's mom hasn't come out and said anything negative about the baby directly (although she can be pretty awful in general), but she has made comments about SD adjusting to a new baby and acted as if it bothers her or it's going to bother her in the future. When I told SD about the baby, she literally was grinning from ear to ear and jumping up and down. This kid was not shattered by the news. We've made it very clear to her that nothing is going to change for her here, and she's going to be loved just as much.