I let no one into my house unless I know that person. It is too dangerous these days. I find no exception for the LDS or for the JWs.
In both cases, I greet them warmly because I truly feel sorry for them. Both are, I believe, victims, but that will not get them across my threshold. If they wish to talk, I will join in for a discussion, not a religious argument, on the porch. As an odd hobby, I study both religions, hoping for the day I can help them to our side of the river.
When they leave, I pray for them.
And back more on topic, I was in a home where an LDS blessing of a meal was being offered. The people around the table were about half Catholic and about half LDS. As I would hope others do, I respected the moment, actually several as that was the longest blessing I ever heard. I did not join in the group saying amen as that is an indication of belief. I believe in only one eternal God, maker of heaven and earth, of all that is seen and unseen. I do not believe that my God was a human on another planet, so I cannot indicate a belief in the person to whom the LDS were praying.
If there were a reason that a person holding the LDS faith were in my home, I would not invite him to offer a prayer, but, if he did, I would be respectful. While I do not believe in the exalted human to whom he prays, I do not think it would contaminate my home and I really don’t understand how we can hope to lead others to the truth of the Catholic Church if we alienate them.