I also would not heat the coop for the reasons given above. Since you have been using a heat lamp, wean them off it by gradually lessening the amount of time you are using it.
I'm sorry for the loss of your father, that's a tough one to go through. It's nice you have his flock now. Give your father's flock and your flock time to get used to each other before trying to mix them together. If you give them separate spaces in the coop and run where they can see each other (but not touch each other), that will help them get acquainted.
So sorry on the loss of your dad. You have been given some great advice on not using heat in the coop and lowering it slowly so they adapt over time. Good luck with your flock and welcome to ours!
Hi! Welcome to BYC! So sorry about the loss of your father. Do you have the ability to separate your coop and run so the two groups can be next to each other but not be able to attack? If so, I would do that for a few weeks before trying to integrate. Good luck with them.