Time heals a lot of wounds with chickens, lol. Over the past 2 years I have added flock members a couple times, usually with slow see-no-touch introductions, followed by trial periods. At first the newbies would make their own clique separate from everyone else and at one point I had 3 different...
If you're going to raise chicks, have a plan for roosters. If you can keep them, have a plan for interacting (or not) with your small child. If you can't keep roosters, have a plan for re-homing or culling them before they start to crow.