Hi Karen,
When they removed the left lower mandible, why didn't they re-construct? You said your Mother-in-law dribbles everything due to lack of feeling in various areas. This is one reason I no longer eat in public. I compare it to watching an oversized baby eat.......more on the chin than in the mouth. I'm sure others here have the same problem. You have to make her understand that she must go to her Dr. appointments even if she thinks its back. Better to catch it early than to let it get to far along. Your support throughout this is I'm sure more help than you will ever realize. As well as any encouragement from you for her to hang in there. You said that you are running out of things to say. Just letting her know you are here if she needs you says a lot.
Keep us informed and remember we are here for you to vent at when you feel the need to.
David