I believe its a bonus.
FIL's will includes DH, but as he's not DH's real father, it kinda doesn't feel right iykwim. He is his dad & has been for 20 years, we even named DS after him (middle name). We would prefer the kids to not know he's not blood related if we can help it, but we feel that his kids (the 2 youngest) & MIL should have it all. We are adults. While we could put it to good use, we don't need it.

In my family my grand parents stopped giving presents for birthday & christmas's when we were very young (the younger cousins weren't even born yet)
The idea was that they'd put money away for us instead & we'd inherit it at 25.
I'm turning 27 & haven't heard a thing about it, but I feel it'd be rude to ask. I refuse to life my life according to handouts I 'might' recieve.

I know mum & dad won't have much to leave us. Long as they don't leave us debt I'm happy, lol