I wish I could say something to make the "hating" less, but I am 4 weeks into a flock integration between year-old hens and (now) 11 week-olds. It has been quite an adventure.
I started them, originally, in a mini-coop, entirely seperated from the biddies, but only chicken wire between them.
2 weeks ago, I made a chick-sized opening in the wire, and they could come and go, but the biddies couldn't terrorize them too much.
This week, I removed the partition entirely, but the babies still have 2 sides of their enclosure to "hide" in.
The Ladies are just flat mean to the babies.
It makes me so furious and I get loud and roo-ish when they do, and I am there.
I also spend a couple of hours a day (in a couple of sessions) sitting out there and giving the babies an opportunity to wander out into the big coop without worry.
Saturday, they will have the chance to go out into their new run, outside, and that will be new to everyone, so it will level the playing field a bit, for the new guys.
It isn't an easy or fast process at all. But having done it the slow, tedious way, I can say it is worth it. I would have been just sick if anything had happened to the littles because of rushing it.
I have been more rushed than I'd like because of space issues, which make intergration issues worse.
My suggestion, make sure u have plenty of space for the total number. Gradually integrate, and be standing by for a while to make sure they aren't killing one another in the interim.
Best of luck!