L, The only saving grace here is that your daughter has some place to go and release the tension, i.e., swimming, etc. However, this still isn't enough "control" for her to take care of her health issue.
As for your son, I can see where he could also be my son as well. Hamsters are the best and suggest he get one of those wheel set ups and make sure it squeaks all of the time. Those little creatures are cute as can be and can run on those wheels for a very long time. Birds and fish wouldn't be enough to drive Dick crazy. Snakes and lizzards would be nice as well.
If your son is taking care of the grandfather, he should be paid. After all, this is hindering him from getting a job as well. Wouldn't the family have to pay for an assisted living sitter for the grandfather if your son wasn't there? Your son needs to call around and get an estimate of what it would cost for a sitter and store the information away until a later time when he may need to present it to his father, even though his father won't pay him one dime for the care he has provided to his grandfather.
Dick really has gone back in time to a place where he'll never find the key to open the door to the present.
As for Jane, she may be volunteering in the evening....I find that rather interesting, just as I do the phone calls behind closed doors. She may be up to her old tricks and looking for her next sugar daddy. Don't be surprised if she's gone in the near future. She's not going to put up with Dick and his tight purse strings for very long.
I wish that I could offer you some suggestions/solutions to your immediate health concerns, but I can't. You are worried about your children and their situation and it's understandable. Unfortuantely, it's out of your control until they come of age. All you can do is listen and be there as a shoulder to lean on. That's stress in and of itself. Please take care of yourself. I'm very worried about you.