Your question struck a chord very close to my situation. My older sister (the eldest sibling) has lived with my parents for over 37 years. During that time, she became an LPN, got her Master's degree in Philosophy and Religion, and has worked in hospitals, and taught at the university level. She has benefitted from having free room and board, and my parents have benefitted from having a nurse on site to recognize and respond to medical emergencies that developed as they age.
But as my father aged, any repairs to the house were not addressed until they became an emergency, and my sister lodged the "blame" at my father for not handling it, for not "sharing", "communicating", "hiding" information about "how things work". My other siblings, who have moved away and figured out on their own "how things work", and have lived/managed on their own, are now all involved (yes, by long distance and on-site visits), and we are all amazed at the unrealistic and "hands-off" lifestyle that our sister has enjoyed for 37 years. She is a co-administrator of our parents' estate, and we are working to address immediate concerns for our parents' well-being and survivorship issues, while we try to gently direct her attention to her own future when "all this ends".
And at times, it does appear to be a "beating up" of a family member, and this launches defensive strikes, sarcasm, regrouping, crying jags, efforts to create alliances within the family, etc.
When discussions tend to go off course, I try to recognize the past good my sister has contributed to our parents' lives, and bring the discussion to the present concern: OUR PARENTS AND THEIR NEEDS. I try to limit what my sister COULD/SHOULD help do in the future, while I address what HAS TO BE DONE NOW, by me and other family members, so that individual and group actions are focused and tasked by time and project goals.
It is extremely painful to see the current dynamics, when I remember the moments of laughter, fun, and support we have all provided each other throughout the years. My younger brother and I live the farthest away, and are usually accused of "divorcing ourselves from the family", and coming in with "extreme" suggestions at the 11th hour. Four out of five children have personal income assets/retirement plans in place (as our father did), and are more concerned with addressing the continued comfort of our parents in their home if medically possible, and expenses for the lifestyle of a survivor, and removing any obstacles to assuring them the secure environment they have earned.
None of us want to leave our sister "high and dry", but the facts are that 4 out of 5 of the siblings believe that any assets our parents have accumulated belong to our parents, and should be used to provide all additional care they need, from reverse mortgages, to sale of the house, when it is necessary.
Our sister feels very threatened, and yet has made no obvious plans for an exit strategy. Instead she chooses to sharpshoot our suggestions and efforts, and communicate what "our parents wishes" are, so that the rest of us back off. I know that change is difficult for everyone as we age, but change happens, and it doesn't have to be negative - it just has to be understood and communicated, and alternatives suggested and managed.
Where safety and cleanliness are concerned, "NO" is not an option.
I hope to restore my sister's focus on "her future" as my siblings and I work to meld our talents and opportunities to help our parents' transition. It is difficult, and I have heard venomous responses that I never thought were possible from "my family". The ultimate "good" has to be focused on our parents, and while that may incur hurt feelings, trauma and periodic nastiness, having the support and consensus of other siblings will make the required transitions happen.
I hope that engaging my sister as a contributor, where possible, will help. She doesn't return phone calls, nor will she talk to me when I call our parents. I won't lock the door, I won't stop knocking, and I'm not walking away.