Your pullets are 6 to 7 months old. Are most of them laying? That rooster is 1-1/2 years old. Then you have a hen of unknown age you are bringing in. Looking at your first photo it looks like you free range them, no real fences.
Normally I'd say if most of your pullets were laying and it was only the rooster just let him go. He should mate with a few that are laying and make that entire flock his. Usually with a mature rooster and mature hens (if they are laying they should be mature enough) it is really easy, especially with that much room. I don't give guarantees but it usually doesn't get much easier.
That new hen complicates it a bit though. I assume she is laying? You do not want to train her to lay somewhere you don't want her to lay. You do not want to lock the pullets that are laying way from the nests. With the space you have I'd probably just turn both of them loose and see what happens. There are some risks with that. You don't know where they will roost, it could be in a tree. You don't know where she will lay her egg, maybe in your nest but maybe not. They could even go walk-about, trying to find their old home, though with those pullets there it's not very likely. It's possible the hen would beat up on the pullets but with that room probably not likely. Like I said, no guarantees.
Another viable option if you can is to section off a part of the coop and keep them locked in there for a week or so. That should take care of most of the potential problems I mentioned but you may wind up with an additional nest, maybe not exactly where you want it. It means a little more work for you, building it, tearing it out,extra feeding, watering, and cleaning.
If less than half of your pullets are laying, I'd wait until they are. House the rooster and hen, hopefully in your coop, until they are. Maturity plays into it, not just for the rooster but also for the hen and how she integrates. That is being really cautious but I sense that is what you prefer.
Good luck!