Fecal Incontinence....any remedies?

My situation is different (my entire colon was removed due to cancer), but the 8-9 trips to the bathroom. I don't know if this will help - your experience will vary, but if his stools are runny like constant diarrhea, it might make them more solid and more controllable.

Mayo Clinic advised me to take (more accurately gag down) Metamucil in a slurry (minimal water) to absorb the water in the stool to make things controllable. I take a heaping teaspoon 3-4 times a day. I wait 2 hours after taking meds because of possible adsorption issues. It took a long time of trial/error to get the amount figured out. Again, this is for someone without a colon, his situation would likely use less.

Make sure to use a fiber supplement that absorbs the water - some don't. I prefer to stay away from those with sugar as those encourage runny stools.

That's not a fun regimen, but it's a lot better than soiling oneself 8 times a day.

I agree here that you should try to get your father to have colostomy surgery. I was diagnosed with rectal cancer in 2018. I went thorough chemo, radiation and I have a permanent colostomy. I feel this surgery saved my life. It does take some getting used to. I have bowel movements about ten times a day. I take Imodium and lomotil occasionally to help control this. Going through this is better than wearing diapers all the time like I was doing before. I am 64.

Well, there's a big difference between age 64 and 82. Big drop off. If dad was 64 he'd do it. His surgeon was very serious when he said that the surgery would be very hard on him. Now, dad has lost 40 pounds after he got cancer, went through radiation and took the chemo pills. He's not gained it back. He's 140 pounds. When you get older there are all sorts of complications that can end your life. He is worried that the infusion chemo would've ended his life (25 percent of people over the age of 70 have to quit it, I"m sure it's higher after age 80), and I don't know if after the radiation and pills he was strong enough to get through the colostomy. Now I've not pushed him either way, but we've had long discussions about this.

For now he's on a regime of immodium, lomitil (alternating) and of course adult diapers and maxi pads. I don't know what else to do.

Ps. The oral chemo did a number on his brain. He has trouble remembering things all the time. I can't imagine what infusion chemo would do.

Thanks for your comment.

@rjjacobsen suggested Metamucil. Psyllium husk (what's in metamucil) taken with little water and limiting liquids during the day can help.
Maybe consulting with a dietitian, you could get your dad a diet with a good balance between soluble and insoluble fibers that would bulk his stool without constipating him.
Also pelvic floor therapy migh help with control of the incontinence. I have LARS and pelvic therapy with biofeedback, neurostimulation and PTNS (Percutaneous Tibial Neuro Stimulation) has really helped me.