Trouble with mult-accounters

Just a simple question about people with multiple accounts. There’s a gym in my town at a church and next door to the church is a house where a family live of 4 but these people have roughly 10 accounts which they share across all of their devices (3 phones). They aren’t young either, in their 30’s, a brother and sister who have their mom playing plus they each have a account for their children. Both single parents. So that’s 5 accounts right there plus the dudes girlfriend makes 6 and her son makes 7. They also have extra dummy accounts that sometimes occupy the gym. They don’t let anyone have the gym and will boot whoever takes it from them immediately. The only times you can hold it are from 3am-8am. In the first year they never left the house, and after raids became a thing they would try and join them without coming to meet the rest of the group so we’d make private lobbies. But since friend codes they started to participate outside with us but haven’t tried making friends with anyone in real life, and have started to take the other gyms in town multiple times a day. Sucking the life out of the game for even their own team mates. You can see them logging their family members into gyms because they are usually 2-3 minutes apart showing up in gyms. Can anything be done about this?