Social dynamics vs quarantine?
Hi, I’m starting a Pygmy Cory group and originally got six. Being new to fishkeeping, I lost one to a mistake and another has just disappeared (idk where, looked around tank/floor but no body). I got them three friends to add and keep the group at a comfortable size and I’m keeping those three separate to keep an eye on them since they’re new, but now I’m curious whether the quarantine outweighs the need of both groups of Cory’s to be social? Like is having a group of 4 in one tank and a group of 3 in another waiting to join them stressful to both groups since neither is of an appropriate size? And do the health risks of that stress that outweigh the quarantine, particularly if the tank is just Pygmy corys, a couple neocaridina, and some mystery snails and not like a large number of diverse fish with a lot of potential immune vulnerabilities?
Would appreciate any advice, trying hard not to lose any more and scared of overly stressing them with a lack of company but also of accidentally introducing pathogens — which option seems like it’d keep them in better health?