What should I do?

I understand that this post might break some rules, but I'm not sure where else I could ask for advice, my apologies!

My mom is a wildlife biologist and as part of owl surveys, sometimes they buy feeder mice to feed the owls. We bought six mice and I wanted to keep them relatively comfortable and happy until my mom needed them first thing the next morning. Unfortunately, none of the mice got eaten! I have them in an about 12''-6'' plastic box with lots of shredded paper, a log tunnel thing, and some barley.

I tried sexing them and I think 5 of the 6 are male. I've posted on social media asking if anyone near me needs feeder mice or raises mice and would like another female mouse, but no one has gotten back to me yet. I know male mice shouldn't be kept together, and I'm really not sure what to do!! I would like to keep them as happy as I can until I can find someone! Any and all advice is greatly appreciated!