How do I get my father to use a bedpan?

I just asked my aide if he can do that with my dad try establishing a routine -I'm not with them all the time and my mom is 85 dealing with it after the aide leaves in the AM. My dad doesn't want me to help and of course its too much for my mom to do it all.

Bedpans are painful to use and I would not want to use one either.
Have his doctor order a Sit To Stand. That will make getting him up and out of bed onto the commode, into a chair very easy. If he can hold on to a support bar and if he has some strength in his legs the Sit to Stand is the way to go.
If he does not have any strength and if he can not hold on or have strength in his legs then the doctor should order a Hoyer Lift.
Is your dad on Hospice? If so they can order either piece of equipment. And they will train you how to use it.
(and it sounds like he would qualify for Hospice)
A caregiver is not to JUST get him out of bed and to the toilet. A caregiver should also help with light housekeeping, changing his bed, bathing him, helping him dress. And if dad is "bedbound" he should be moved at least every 2 hours to help prevent pressure sores. And make sure that sheets and clothing are not wrinkled.

You will need help. I'm not certain how Medicare and all that work to help pay for such things, but many on here do.

His memory will get worse. His body will get worse. And yours is already getting worse! You can't keep going with this. There's no magic way to convince a person to do something when they've decided they won't.

If he is still fairly cognizant, you can give him two choices: Hire someone or placement. Because at this rate he will out-live you, and what will happen to him then?

I'm guessing he'll say NO to both, but he surely has noticed how much you're struggling. I'm sure he'd choose hiring help above a facility.

My husband who also was bedridden, didn't like bed pans either. I don't think I would either as that is such an unnatural way to go to the bathroom, especially poop. I did hire an aide to come for one hour in the mornings to put my husband on his bedside commode. That worked great for me as eventually his body got used to pooping in the mornings, and clean up was so much easier. His aide held him up while I wiped him and cleaned him up. He very seldom if ever had an accident after that. My husband also had a supra pubic catheter, which made life for me a whole lot easier too, as all I had to do was empty his catheter bag twice a day.

Now I did have to hire an aide that wasn't affiliated with an agency as most agencies require a 3-4 hour minimum. They are out there. I got my aides name from our Senior Services, as she had worked for them for 12 years, but left to go out on her own.

Good luck and God bless.