Locked room for breakables when grandkids stay?

Talk to your son & DIL and see what they think is the best way to handle things. Your grandchildren need to be taught not to touch without asking first.

I am going against the grain here it seems, I would lock the door. Or at the very least, set boundaries that the room is off limits. I just don't want to invite more trouble than I want right now, IMO. No sense in it.

I would feel the opposite of it were just a quick visit or even one overnight stay.

*any precious breakables are put above their level

We have little ones who are constantly barging around energetically, any precious breakables are put their level but some are within reach and if I or their parents see them go for it we let them hold it for a second and explain how careful we have to be with nana’s things, then we distract them and put the thing back. Have so far lost the beak off a pot robin and a pot cat lost her head, but tbh I break more stuff than they do, am a terrible klutz.

Mine have broken more since they were adults! Mostly glasses.

Either move things up above the child's level or pack the precious breakable away when they stay.
Unless you live in a mansion of course in which case lock the room.

I must be lucky because none of our lot have broken anything much except the odd glass tumbler by mistake. My kids didn’t ,either. Don’t need to tell them.

Looking to the future, you might need to rethink the location of your collection or you'll be a nervous wreck whenever the family visits!

I suppose it depends how big your house is, and if closing off one room is going to make the rest of the house crowded.
We have a large collection of glass and, touch wood, we haven't had any breakages as the grandchildren were taught not to touch. We don't allow indoor ball games either.

Not that.

If the 3 year old breaks something of sentimental value I would need it and it would be part of our family history.

Like the time 7 year old (play) wrestled his pa to the floor and hurt his wrist. It's families.