Too many people eviction notice

I am staying in 2 Bedroon Apartment on rent in Louisville, KY with my wife and 10 months old baby. Now, our parents visited us (Father & Mother) for 3 to 6 months. There are total of 4 adults and 1 baby (10 months old) = 5 people. First they ask for 75$ for each person application fees, which I agree to pay.But now, According to the apartment management, housing law of kentucky does not allow 5 people in 2 bedroom apartment even though 1 of them is 10 months old baby. So, they have ask us for the eviction. Can anybody tell me, what can I do against it. Is there any website or organization, which can tell me about these laws. please suggest!!