I have 3 cats ranging in age from 9 yrs to 15 yrs old... they have all lived in my house for years with no problems. Recently I brought a 3 yr old cat into the house to live... its been months now and the new cats is still getting into fights with two of the cats that were her before - and this morning my cat had a big scratch on her nose from the fight. Is this normal? How much longer will it take for them all to be friends?