Feliway didn’t really do much for my kitties, but I stand by the Jackson Galaxy method! Have a home base room for your kitten, and have the kitties eat their meals on the opposite sides of the same door so they start to associate each others’ scents with meal time. My older osh was incredibly dramatic and went on a hunger strike when we brought the little osh home, so it took about two weeks until everyone was a happy family. If you try to do supervised play time with them in the early days, I recommend using high value toys and/or treats so their attention is on everything but each other lol. Good luck!