People did that to my parents many years back. A friend said he would take care of it. He showed up with a few drunk buddies and went in the front door with the people there. The began throwing stuff out the front door as quickly as the could. They left with a warning to return the next day and continue. They people were gone and everything went to the dump.
It’s amazing that squatters think they have rights against other squatters. The law is an ass. A squatter can break in and change the locks but you can’t go into your own property and change those same locks.