I would separate...due to size and give them more room. Kiddie pool they will be able to hop out of shortly...they grow fast! I use a large plastic tub...maybe 4 ft long and 2 feet wide???? I put the heat lamp on one side and they can move from one side to the other depending on their temp/comfort level. The sides are high enough that they peek over, but do not hop out. Pretty sure I got mine at walmart cheep. easy to clean too...I just let the little quacklings roam and swim while I hose it out, dried and put new bedding down. That should hold them over until you are ready for them to be outside. Box with same idea would work also, but you would need plenty of bedding so it would aborb their poop