How Do I Make This Happen and do you think it is fair?

My APBT and I visit my mothers house like once a month. My mom has 2 dogs as well, but hers are poodle mixes both under 15pounds. My dog is 44 pounds, but I have treated her like a lap dog her whole life(she is 14 months). I dont mind, I think she is a medium sized dog, whereas my mother swears she is a giant. Well anyway, my mom now decides she doesnt want my dog on her couch anymore. She has always been allowed on furniture at both mine and my mothers house. Now my mom decides for NO reason that she just dont want her there. Its because my dog is excited to see my mom and sits there and stares or puts her head on my moms shoulder. Well my mother says its not right because she is too big to do this. Now she said when we go back, my dog isnt allowed on the couch. She was yelling at her to get down (which she would) but then jumps right back up because she sees my moms 2 dogs on the couch. I dont think it is fair to my dog. I also dont see how I can keep mine off when she has always been allowed up. Plus she sees the other dogs there. And she IS allowed and ALWAYS will be allowed to sleep on my couch at home. I could never give up my snuggle couch tv time with my dog. I just dont see how it will work. Any suggestions please?