We have always had room sharers. At one point, we had 3 in one room, with bunkbeds, 2 on the bottom and one on top.

Now we are down to 2 in one room. They are 6 and 8 and have bunkbeds, which work well for space, but they usually end up bed sharing still anyways. Like 95% of the time. When they are unhappy with each other, they will sleep separately. Or when the younger one is snoring, lol!

I would be nervous with the younger one going on the top bunk bed, too. Might work okay if they stayed on the bottom but there will always be that worry in the back of my head that the little one would get up there and fall.

is there the possibility that they may each end up in their own room one day? I would maybe go with one bed to share for now.