Hi!
It's much harder, of course, to get interaction when you're not the one taking your child out, unfortunately. It's all about moms talking about mom stuff. I see that on days I work and my sitter has my son.
but I wanted to suggest one thing. On Monday and Wednesday mornings at the Lincoln Park Zoo they have a sing-along.
It's in the Farm-in-the-Zoo at both 9:15 and 10:00 am. My son is 11 months old and I go each week with two 14 month-olds and their moms.
It's fun. It's free ($1.00 optional donation), and it's a great place for your child to interact with other kids a bit. Well, at least he can look at them!
If your father-in-law has more questions, he can email me. And I'll make a point to look for him there.
Come summer, he'll have all the playmates he needs in the parks (Oz Park and Bauler are great, but may be too far for you).
In the meantime, hang in there. Winter is halfway over!