I don't know if that's too many either, I guess you'll find out as everybody grows
I "think" if the egg laying pair didn't beat up anyone you "might" be OK... for a while...I thought they were fairly peaceful for cichlids...Or your fish might be "bossy" (aggressive) like FFs. It's good you have a plan for either future! Sometimes it helps if they grow to adulthood together & establish a pecking/breeding order...time will tell...
After discussing with my husband, he thinks we had just 1 severum that came with a very too small tank & we didn't have it for too very long. I just don't remember after all this time, he might be right (every once in a while he is, lol).
I'd love to see pics of the new turquoise sevs once they get used to your tank. I'm not sure I can always differentiate between them & green...a lighting/substrate thing?
Oh I see you were typing too...