Well, follow these directions and you SHOULD get a password for your grandparents. If you've already done EVERYTHING, then please tell me. I'll try to help. <_<
1. Make sure that the mother has left the baby.
2. Once you have named the baby, go to yhe book icon.
3. Go to History and press B.
4. Press A so that your grandparent willl show up.
5. Press B to view the grandparent's information until you get a screen saying, "Password for PC!"
And...that is all! Hope it works!
EDIT: When you visit your grandparents, tell me what souvineir you get, post here or pm me. Post it like this:
Item Number. Item Name: How to get it
I need it for the souvineir list on the Tamatown board!