got rid of - because she fought too much with our established 17 year old cat

Advice needed here...

At the end of July I will be integrating two new cats into my already-two-cat household, along with the two new cats' owner.

I anticipate considerably less difficulty integrating the owner than I do the additional cats.

Can anybody offer advice on how best to do this, with minimal bloodshed and caterwauling?

The two existing cats are a male and a female, as are the two new cats. Both male cats are at least 10 years old, the female cats somewhat younger. I am afraid that both male cats are territorial by nature.

Current plans are to keep them separated -- two cats upstairs, two cats downstairs, and I have cut an 18" square hole in the door to the basement, said hole covered with a screen whose mesh is about 3/4" square.

We'll alternate the upstairs and downstairs cats every couple of days until the cats come to some sort of accommodation with each other.

What else can we/should we do?

tanstaafl.