Great "Q"! This is going to be long!I'll work from the eldest to the youngest:

Puca(tabby, dsh (f)) becomes- Pooky,Puca luca loo, contrary knickers!

Juju(full black,dsh (f)) becomes- Doodoo, Ju ooh, Little cow, girlie!

Willow(grey &white, dsh(f)) becomes- Willow ello ello, Wills, willikins!

Candi(grey tabby, dsh(F))becomes Bandy Candi, Candi wandy woo, cutey girlie!

Pearl(full grey, dsh(f))becomes the beauty, pearlie girlie, Pie-elle!

Harry (full black, dlh(m)) becomes bully, brat, Harry baby, Dirty Harry, the fuzz, Harold, Haroldo, my Best Boy, Biff, The Reverend Harry Bob Cat!

Rufus (ginger &white,dlh (m)) becomes Rufeo, Mr. Rufus G. Bagpuss, mad cat, Pumpkin puss,roofy baby, my little man, Chuck!

Phew! that's it !