Well if you didn't you didn't. Don't stress about it now, just watch both sets for any illnesses. People went for years without doing it and while it's the best thing to do now that we know more, what's done is done in this case.
Having two who are now lowest on the pecking order is better than a single. at least they can pal around together while avoiding the others. As long as they aren't getting nasty enough to draw blood, a peck and some squacking is very normal. If they get too too violent, you can go several different ways...
First, (and my personal choice) If it's one or maybe two most dominant hens being bad, then take those out and put them in a crate or seperate area to give the new girls a break and allow the others to make friends with them. They'll likely be nicer without the bossiest ones to start trouble... this will also take the top hens down a peg or two by taking them out of the mix.
Or, (this one has value too) you can just wait another day or so, (if they aren't roosting together tonight, go in tonight (semi darkness, use a dim flashlight) and slip them in among the old girls, sometimes they wake up in the morning and things go smoother)
Third, (and least value IMO) take the two newest ones out for a while and try again later. Problem here is, it'll just start all over again... unless you have a next door pen they can stay in a while and see and meet and greet close enough ... that has some value.
//edit// it took close to a week last time I merged groups for the worst of the meanness to stop, and then a couple more weeks for them to start to really mingle. now after several weeks they still break up obviously into their old groups, so don't expect them to be bff anytime soon!