My poor dog (Sorry this is long)

I'll start from the beginning so this whole story makes sense. My parents recently separated and my mom and my sisters and I had to move in with our grandpa. We also have 6 animals that he agreed to take in. 3 cats and 3 dogs. Almost all of them are well behaved indoor/outdoor animals and have adjusted to their new living space okay except for my golden retriever. She's still pretty young- about 3 or 4- and she's used to having a big yard to run around in all day. The only times she would come inside were if we left the house or at night. She would go on the back porch or in the garage or sleep in one of our bedrooms. At my grandpas house at first she was tied to a long leash in the front yard so she could roam around a little without running away which was fine it was the best we could do for the time being. But then a neighbor knocked on the door and complained because she would bark occasionally at people walking by. It wasn't aggressive or anything she just wanted to greet the people. But my grandpa moved her leash to the porch which had yard access and it was less noisy for the neighbor, not ideal but it was still doable. But then yesterday I noticed her leash wrapped around the porch, shortening her leash, and allowing her little to no yard access. I asked him how she managed that and he said that he did it on purpose because he was sick of the dog digging holes in his yard (which is not any prize believe me). He said she could just poop on the porch everyday and he would clean it. I looked at him in disbelief and told him this was cruel and should be considered animal abuse and he laughed in my face. I asked my mom to talk to him about it and she just said it was no different than when we were at home but it's not. She is getting mistreated and my mom would rather brush it off than face my grandpa. Now he's acting like I'm being ridiculous and demanding. He has no respect for animals or even humans that have different opinions than him. I don't want to tell him what to do in his own house but I care about my dog. How am I supposed to treat this situation with such a stubborn person?

Edit: I also take her on walks as often as I can to get her energy out so she'll behave better but everyone in my house is at work or school (except for my grandpa but his lazy ass won't do it) all day so I can't do it constantly like she needs.