Hello and Welcome!

I suspected from your write up that you were from a dog back ground. LOL Dogs basically sniff butts and run off together for a game of chase!

Cats are a whole 'nother story. You've done well, getting the second while they are both young, as the process will be MUCH easier. Introducing an adult cat into a house of adult cats can take 3 weeks or more.

Make sure you have 2 litter boxes. Other than that, take it slowly. They will come around quickly due to their age, wanting to play. He is thinking THIS IS ALL MY TERRITORY, and she is thinking OH GOSH I'VE BEEN PUT IN A BAD SPOT HERE but they will come around.