What would you do?

Separate, without a doubt.

They may be underage in their home countries and for that reason alone I would put them in separate rooms.

Separate rooms.
its not for you to facilitate anything which may be going on between them!
Your son or daughter will be happy also.

Erm have we not heard this one before?

Separate rooms and cornflakes spread on the floor between the rooms.

Luckygirl

Perhaps a trip to Shoezone?

Always separate rooms. With or without cornflakes. As a parent of 3 DS, we felt a responsibility to the parents of the visiting girlfriends when they were growing up, albeit this was a long time ago.
Still I think my DC and DGC would still expect this of us. They are your guests so treat them as you would any guest.

Separate rooms, I think. I suppose you could grasp the nettle and ask your grandson's parents what they think. However, the final decision is yours to make as your grandson is staying in your home.

Separate rooms. They’re only 16, I would base my decision on their age. If older, 18 plus, may offer the same room, if they wanted it.

Separate rooms with plimsolls and onesies, that's covered everything and they should be allowed to use the lavatory when needed.

Speak to your GS's parents to get their view first.

Can I respectfully point out that if two young people decide they want to 'do the do', separate rooms will make no difference at all.

sodapop They just aren't getting it!!

Penny has just dropped "Schools out for summer" ????

Thank you for your views. I had decided to put them in separate rooms. Your comments have helped.

Are you happy with them having sex? If so, own room.

Otherwise, separate.

They will have sex if you allow them in same room

Separate. It’s your house, your rules, though you don’t have to announce that.
My daughter surprised me when she told her boyfriend (now husband) that they had to make US feel comfortable.

separate rooms

I thought the same as you as soon as I read the OP Jane10 then wondered if it was just my suspicious mind? I think you’ve got it spot on though !

Jane10, sodapop & gillybob,
Well, four of us have caught on!

I too have caught on but do not like people being left puzzled so should explain that there are/is a trolls who is advertising Shoezone (there now, I've done it too!), onesies and issues about children at school being allowed to go to the loo. There is an assumption being made that this post falls into a similar category.

When faced with the same dilemma my M.I.L. Made up two rooms upstairs and slept downstairs. She left the choice up to them. She did stay up till 3.30 in the morning and waited for them to come home from clubbing in the city. Gave them tea and bacon butties when they came in. Lol

Years ago, our son said I was being' disrespectful' to him by preparing separate rooms for him and his girlfriend when they were in their early twenties. I explained that we were entitled to feel the same as this was OUR custom.
Two rooms, no cornflakes.
She was pregnant less than a year later and there was a rushed wedding. He never said so directly but his oblique comments to me and to other family members made me feel that not all was satisfactory. They have worked things out now but I am glad that I was not complicit in this pregnancy

Read Luckygirl's post wigeon and coast35!