Question: 

"My father has a wound, and his hired, live-in caregiver does not change his dressing as she promises to.  She works for my father, not an agency.  What do I do?"

Answer:  

One way to think of this is that your father has become an employer, and he has an employee who is not getting the job done.  This is a dicey situation because he may not be capable of acting as an employer.  There is also the possibility that he is not comfortable directing his care.

If your father is incapable of directing his care, then a family member must be given the responsibility to pay and direct the caregiver, even if your father is the funding source.  An individual who needs someone for live-in care likely needs someone to oversee the care as well.

Speak with your father privately, and insist that the responsibility of paying and directing the live-in be handed over to someone else, preferably a child who can be trusted to act as an employer.
 
Wounds that are not managed, particularly pressure-caused wounds, can result in a serious situation.  If the caregiver has accepted the responsibility then the work needs to be done.  Dad is likely to say "It's okay," out of fear and the desire for a good relationship. Make one of the children the boss, or "the bad guy," by enforcing the expectations.

Circle back daily to check on the wound if possible or as frequently as you are able to check on progress.  Here's a trick, tell the caregiver to date the bandage with a marker.  You could even have Dad take a picture of his wound each day and text it to you.

For a person with a wound, I would also strongly consider a few nursing visits to measure that wound, having the nurse work with the physician to achieve a resolution.