I posted a couple of days ago about a problem with my Macy Growling at her little sister. Well, I will admit that I did give her a light tap on the snout when she did it with me holding her. Since that time any time that Sandi has got up on the bed she has been fine. I make sure that I praise her every time Sandi jumps up on the bed and say that's a good girl.
When I had to Lightly hit (I hate that word) Macy it really killed me to do it but I also could not let it continue as Macy is 45 pounds and Sandi is only 12-15 pounds and I was afraid of what would happen if it escalated. In the past as with this I try to use positive reinforcement / praise.
I hope that you can get it settled out.