New Baby in Family After Bereavement

I hope this ok to post in here. My much beloved MIL passed away at the tail end of the pandemic, on the other side of the world. It was devastating, made worse that she insisted we not make any attempt to come be with her towards the end. She worried we may not get back into Australia.

My FIL is a classic stoic Scotsman, he was her devoted carer and worshipped her their entire life. He handled everything to do with the house, moved into a flat in Edinburgh alone. He has a lot of friends and family around him and he gets out and does things. He still grieves very hard for her, sometimes we talk about it over text when he’s been in the cups. He still uses her Facebook account, too. They also lost a son a bit over a decade ago, he was in his early 20’s. So my partner is the only remaining family member. But the pair of them don’t really communicate, for whatever reason they tend to communicate especially emotional things through me.

FIL rented an apartment in our city for next summer, three months. He has other family and friends in this country and has plans to do things with them. He’s coming primarily because I’m having a baby. His own son is 42, and this is FIL’s first/only grandchild. It’s been hard to get a read on his feelings about it, and of course we all wish MIL could meet the wee bairn.

So my question is- what are your suggestions for honouring the grief my partners family has endured, while also bonding the new baby to his grandfather? Are there cliches I can avoid? Ways to celebrate that feel… inclusive? It’ll also be the Xmas holidays too which can also be hard. Mil was an incredibly warm, vibrant, curious person. I still find it hard to believe she is gone. I also feel my own grief is relatively small, I only knew her a few years and he’s lost his partner of 45 years. I’m open to ideas/perspectives of all sorts.