These are the ones we've found for DD. Most of the others I've looked at were too focused on sibling rivalry, and I don't think I want to introduce that idea.
Baby on the Way (Sears)
Waiting for Baby
The New Baby (Mayer)
I'm a Big Brother/I'm a Big Sister (Cole)
What Baby Needs (Sears)
There are a couple episodes of Arthur that cover adding a sibling, particularly the series with Binky's adopted sister, Mei Lin.
Wife to my best friend
DD1 (4/15/10) and