If you can try to be patient. Nothing lasts forever and over time (only a few months since MIL died, so very raw for them), you may well find that his visits start to lessen. I had something similar with my DH, when a member of his family was ill and he spent a lot of time dealing with them, while their immediate family seemed to do very little. It annoyed me at the time, but I kept quiet, as every time I mentioned it he was defensive, but over time when things settled down, the visits became further and further apart.
Fibre broadband and house phones
do you have plasterboard on your walls?

