I thought about this all night long, and I have a few other ideas which you may want to consider.

Before kitten arrived, where did the older 2 sleep at night? With you? And who sleeps with you now? kitten? Maybe kitten should spend a few nights in another room and let the older ones snuggle with mom again. Make sure the kitten has a toy or 2, litter box and water, and the room is "kitten proofed!

Who gets food in their dish first? Kitten? Feed Grouchy first! (I am finding this very hard not knowing the cats' names, ha ha!)

Always pet the grouchy one first, then the kitten. Always say grouchy's name first, then kitten's. Always welcome grouchy first when you get home from work, then kitten.

Having them touch noses is good, I am surprised you added that, it means they are making friends I believe! So why the fuss later on I wonder?

Also try this, but make sure you clip nails on grouchy first. Hold and cuddle grouchy, telling her what a good girl she is. Walk over to kitten and let them nuzzle. Be prepared to move back the minute anyone looks agressive, and to grip the neck as follows: The best way to get the attention of a cat you are holding is to take a firm grasp of the fur and skin on the back of the neck and pull up. You know how mom cats lift babies to move them? Well, you don't want to actually lift, adult cats can no longer support themselves like kits and you will injure the cat, perhaps needing to rush to the vet. But if you lift slightly, just so some of the weight is off the front legs, THE CAT IS IMMOBILIZED, and you have her undivided attention! I use this often during bath times, to immobilize the cat. I also do this when I want to "lecture" a mischief maker! It reminds the cat that YOU are the dominant one, YOU set the rules, YOU decide who gets what treatment. It puts you as the alpha cat in charge of the colony.

I hope these thoughts give you some more ideas how to help calm the chaos in your home. Best wishes!