In-home personal care team?

As my mother‘s Alzheimer’s progresses, we have reached the point where she needs a caregiver with her 24/7, and we are looking to bring in a team who, together with our current excellent caregiver, could provide around the clock coverage in mom’s home. I’m very interested in any experiences people have had with in-home healthcare, good or bad, and particularly with round the clock care. Although I am open to working with an agency, my preference would be to cut out the middleman and have a direct employment relationship with the caregivers, but I’m not sure how the logistics of that would work In terms of ensuring 24/7 coverage when caregivers inevitably need time off work for illness, vacation, etc.