Tell me about siblings bedsharing!

It's starting to happen in our house and I would love others experiences.

DS1 will be 4 in Feb and DS2 is 2. When a caregiver is putting them to bed they often fall asleep in DS1's bed (twin on the floor) or DS2 will join DS1 in the night. They both tend to sleep through the night when they bedshare. DH and I both work evenings for a week or two at a time a few times a year (they have a lot of evening babysitters sometimes).

When they don't DS2 will end up in our bed a few times a night (we are working on this).

I was about to get a small loft bed for DS1 and DS2 would sleep under it. But I don't want to ruin a good thing!

Does anyone have experience with this?