When you get ready to try again, place them in a run/housing next to the existing ones so they can see each other for a couple of weeks. This can help (sometimes) may integration go more smoothly. There is still going to be some picking/pecking/chasing and scuffles until everything is sorted out - this can take time and patience.I placed them in the middle of the night. Many suggested this was an excellent way to integrate. Yeah, not so much. I have cameras so I watched them like a hawk and ran to them immediately once it started.
You want to have plenty of room, probably add an extra feed and water station and have barriers and/or some places where the younger ones can get up and out of the way of the older birds.
Look up and do some reading/research on "see-but-don't-touch" integration.
Hopefully with a few adjustments, things will get better for you.