Advice needed on trapping new momma

I have been trying to trap a cat that was abandoned. she couldnt hang out in a harder area to be trapped!! finally the apartment manager allowed me access to a gated area to set my trap, when i noticed she's been nursing. I put food in the trap without setting it, to get her used to it, but i cant take her away from her babies. Ive been watching her and i think i know where they are (under apt.) i dont want to ask the manager for access because he seems like the type that will seal it off. he is allowing me access to trap the cat because it is a nuisance to him (he is a nuisance to me) what should i do? i dont want to get caught sneaking in another gated area to creep under the building. i will take the mom and her babies in to my home and find the babies homes and keep the mom ( and have her fixed) what should i do? i really need help. this is consuming me. and the mean man is wondering why i havent trapped her yet. i keep telling him im getting her used to trap. i cant tell him about the babies. he is not a cat person at all. i am desperate and will try anything.