Is it bad for cats to stay in one room let me explain...?

Ok so myself n my husband r experiencing very hard times And may hav to move bac in wit my parents for a couple months just until we have jobs with our degrees that we will hav in august..the question is. we hav two cats a year old tht we cant get rid of they truely are my babies but my mother is allergic. how bad would it be if they stayed in one room full of their toys n litter box n so on and we have a penn outside the let them out in occasionally...this would only be for three months max i have harnessess n leashes to walk the also every day? please i am not trying to be cruel i love my babies i am trying any way i can to keep them with me i need them! please help with any ideas!!!!