Thinking they mature around 4 inchs and that's when the aggression can start. I understand not wanting to give her up. My male has more personality than any fish I've ever had including oscars,Red Devils,jaguars and wolf cichlids.
As a lone fish a 40 gal breeder may be ok because of the width and being a female but a 4ft tank would be better.
Can you rehome the angels? I don't really know anything about angels so hopefully someone else will chime in about them but I would think they would need a larger tank because they do get big too. Thinking around 5-6 inches long and at least that tall
Angels are also soft water fish, and hard water conditions are less than ideal.