[cypher]

Unfortunately the dolls house isn't really suitable for a hamster, the floor space isn't really enough for a syrian, they do best with something around 100x50cm, all on one level, you wouldn't be able to put a deep layer of substrate in without it falling out, even if you blocked the mesh off I'm not sure it would be high enough for either a good deep layer of substrate with a house on top of the substrate or for a large enough wheel.
It's not advisable to have two hamsters in one divided cage like that even if it was suitable otherwise, they would still be aware of each other which could cause problems, being wood it could be chewed through too.
I would look for a more suitable cage for each of your syrians & not use this at all tbh.
If you need any suggestions on the best cages let us know which country you're in & someone may be able to help.