Ah yes.  So here it is:  I just got some advice back on another page
but more would be appreciated as well.

Two cats living together very happily (with ex boyfriend).  I go and
get my old cat.  She sniffs my whole apartment etc, and then starts
crying.  I think she's missing her buddy, so, literally less than an
hour later, I go get her little buddy (both females).
When cat 2 arrives, cat 1, my cat, flips her sh.t completely.
It's a new environment for both so I get that.
I can't really sleep knowing that they might attack each other.
You would THINK that cat 1 would recognize cat 2!!!???? She's being so
hostile toward her!!!!

PS
They were living together and super cuddly for a YEAR!!!