DIL moving 400 miles

I’d imagine it’ll be up to your son to facilitate any visits with your GC when he has access.

Your son has to make it happen.

On your son’s contact time. Has that been agreed between them yet?

I’m sure your son can arrange this, can’t he- On his parenting time?

Are you on reasonable terms with your DiL? Would she be amenable to you writing to your grandson and sending him little things?

We keep in touch with our granddaughter - intermittently because she doesn't always reply - online using an app designed for children. It allows messaging, speaking and video calls. Obviously this depends on the age of your GS.

Other than that then, as others have said, hopefully your son will give you a chance to spend time with him, or at least speak to him on the phone. That's what ours does.

As the others have said, on your sons time.

That doesn’t mitigate missing him, but what will happen.

Do try to remain on good terms with DIL as well. Shes your beloved grandchild’s mother. So it’s to his benefit that everyone is on good terms

Can only reiterate what's already been said whogoesthere it will ultimately be your son who facilitates your contact with your GS.

That said, if you have a reasonable relationship with your d.i.l. and this continues after the divorce, she'll hopefully allow telephone conversations to take place with you as well as cards and small gifts.

400 miles is a long way, will your GS also be living that distance from your son, his father? Presumably he has agreed to this move if they have joint custody.