Huntington's Help

I could really use some help. I have been in the LTC business for 12 years, but have NO Huntington's experience. My father-in-law has Huntington's and moved in with us today. He is what I would call middle stage. His coordination is bad, he's lost so much weight he's skeletal. I can't understand him most of the time. He and my mother-in-law no longer live together. Because of the mild dementia he has been displaying it led to "near blows" by each party. My father-in-law then moved to his daughter's nearly 2 hours away. He had been driving to our house once a month to spend the weekend with my husband (who is his step-son), myself and our 2 young children who he adores. The last 2 months after a stay at our house, he returned to borrow money from my mother-in-law, claiming he was broke. We have no idea where his money was going. My mother-in-law, can be a bit overbearing. She has no patience and believes she is right at all times. She also feels the need to tell everyone around her what to do in an unsubtle way. She of coorifice called my father-in-laws daughter and accused her of stealing his money. He now wants nothing to do w/ his wife in any type of financial situation. Fastforward to today. At my father-in-laws request, my husband will be opening a joint checking account w/ my father-in-law. Is there a nice way of helping him w/ his finances? Does anyone have any suggestions on how to be in control of his checkbook without making him feel like he's not in control? Right now independence is a HUGE issue with him. I understand that as I have worked long term care for so long. Any help I can get would be great.