Sleeping Arrangements

I have a two-storey house with a main floor playroom (its our dining room) open concept to living room (not a huge house, so its literally within feet lol) I have one spare room which can only sleep 2 kids. I Have a 9m, 3.5 yr old (siblings) and 2 year old. I am concerned pairing the 3.5 and 9m old together but not sure where to have these kids sleep? Does anyone have kids sleep in the playroom if its mainfloor? If so how do you make it successful and get anything done? Im debating whether to have the two toddlers down here with me and the baby solo upstairs. Anyone have any tips or best practices? I am worried the 3.5 yr old may be a tad disruptive. Also, What are your toddlers sleeping on? I need to invest. Parents supply playpens but not cots.

I use play pens and cots with sheets. I use the three bedrooms upstairs. Three in my room, one in my daughters room and one in my sons room. I have had an older child, three years old not needing to nap as long and kept the others up so I brought him down to main level where my playrm is also. He slept on the couch. I have also brought down a cot and just put it in the middle of the floor. It worked well he slept solid and didn't wake easy so I was still able to clean up and do my stuff around him napping.

I have little house too. I have under 2 in pack n play in second bedroom and over 2 on cotbed in our room. Cot stack at end day in corner.