My three mice

Question
Recently cleaning a box in my basement, I came across a young/little mouse and since my past hamster died I decided to bring him out from the dusty room and into a cage. So far it's gone well and I have had him for a month now, I recently caught two mice in my house and I'm surrounded by some parents that say "no", and my grandparents say "why not". Their main fear is disease and I told them it's possible yet unlikely since we live away from cities and near more forest type areas. I fear that these two mice could be mates as I caught them (together) and I fear they have babies or will have babies. What action(s) should I take to make sure these two make it through the winter so I can let them go in spring? I was also wondering if I could place these two mice with my other mouse in the same cage? I'm not sure if they are territorial or anything, but I'm also going to put an additional cage so the three would have room if I was two put them all together. I have confirmed they are a "House Mouse" breed.

Answer
Dear Shane,
thank you for your question.
I recommend letting all the mice go again. They are wild animals and should be allowed to stay that way. The two you caught just now can be put outside in a sheltered place, for example near a shed or a place with lots of undergrowth and leaf litter for them to hide in. They will survive the winter without problems, they were fit enough to survive until now. The other mouse needs to be kept inside until it's warm again, he's already used to the warmth in the house. Don't handle him too much so that he doesn't get tame and can be released again. He will need a huge cage in the meantime, with lots of things to climb and food that's scattered in the bedding so that he learn to search for it. Don't forget the animal protein in the diet, he will need insects like crickets or mealworms at least three times a week.

Diseases like Hanta Virus may be a problem depending on where you are, although House Mice usually are not infectious even when they should carry the Virus.

If the two mice are a pair, you will get babies when oyu keep them, about 40 in three months (and that's when you separate all the babies and just keep the two together, otherwise it will be more like 400). They won't breed during the winter normally, but if kept inside, the conditions are good enough.
I hope I was of some help to you
Jennifer