It sounds like their dog is being domineering, they are the pack and its the leader dog.

They need to get it in training and spend money to get him well trained.

My dad has spent tons of money in training our dogs,we work hard on having nice dogs. We have gone and asked help time to time. Just recently we did and sure it costs alot but so does bitten off thumb or infections etc. He will get worse not better and he will really attack them bad or someone visiting or a small child. they need to get help immediately. they are not good owners in allowing this to go on without asking for help and getting it.

Also does the dog have toys of its own to play with. IF it doesn't that may be why its picking everything up. He need toys and needs to be kept busy and walked and wear him out.