Susan, with Mom I just replaced her underwear with the light weight pull ups that fit. She didn't have an option. I didn't discuss it or make a to do about it. They just appeared. She did ask about them once and I told her they were her new underwear since her old ones were worn out... and let it go at that. She was no problem to get into the pull ups when there was nothing else to wear
So don't discuss it. Don't give her an opportunity to "not go for it". You just make them, and only them available, and they wear them. At least it worked for Mom
She might be happy to be rid of the pads!