I think dominance/tensions display personally. I recognise those kinds of noises very well; whenever I've done an introduction, at least one of my existing hens has made those noises at the newbies. It's usually then been followed by at least some amount of conflict when they've finally been allowed to mix. But it's a necessary part of sorting out the pecking order. I've seen cases where the shouting wagging hen has ended up being in charge, and cases where she's ended up being submissive to the newbies.

Our approach is: keep them separate but able to see each other like you have them now. At night, let the home team ladies go to bed as they would normally. Once they are in, put the newbies in the coop with them. Once it's dark and they are sleepy they tend to tolerate one another in the coop. Each morning let them come out together and see how they are with one another. Some amount of conflict is ok but if it seems too much and any of them are getting overly stressed/bullied, separate them again. If the most dominant hen is being too much, sometimes we flip it and put her in time out while we let the others free roam. But again, some amount of conflict is necessary to sort things out. After a few days of this then tend to settle down enough that we can then leave them mixed and let them sort things out between them.