What are the best tactics to help Mom take a shower?

Maybe it scares her to have water pouring over her and she thinks she's gonna drown. When my father-in-law died and left my mother-in-law alone, I started watching out for her. I had NO idea that she had been standing at the kitchen sink doing the PTA (pits, tits, ass) method of getting clean, for who knows how long. She has dementia, but the problem for her about the shower was that she was afraid she was going to fall. She didn't have a walk-in shower like she does now at her asst. living place, so stepping over that tub scared her. Plus she still doesn't like water running over her head in the shower. So we removed the shower door, got a bench that spanned the length over the tub rim. Then she could literally go from the toilet to inside the tub without having to worry. She already had a shower wand. I guess my point it, even though it was kinda gross to me, my mother-in-law never did stink even though she was only doing the PTA method. If your mother is capable to keeping stuff clean 'down south' so to speak doing that way, what's the harm of letting her? Good luck.