Hire in home help on his dime, to come in for at least 4 hours per day. The caregiver can help with cleaning, cooking, running errands, showers for dad, companionship for him, changing bed linens, laundry, etc. The siblings should not be in complete charge of his care; it's too much to expect. At 100 years old, he may require more care than can be provided for him at home, even with caregivers coming in for 4 hrs a day. If so, look into Assisted Living or Skilled Nursing, depending on his needs and financial picture.
At 100 I would check out some homes for him. My mother is 97 and in AL, she is doing well. My brother is 65 I am 75, we are too old to care for her and neither of us is clinically trained.
If he's 100 the youngest of you is likely in their 60's so I think it's asking too much to expect any of you to provide hands on personal care. I think it's likely time to look around for an appropriate facility.
Good luck.
Good Luck!