Most Depends type underwear tear down the sides for easy removal while prone. Depends isn't the best or cheapest option.

I've found that toileting on an hourly schedule works well. Very matter of factly take her into the bathroom, pull down the underwear, and help seat her on the toilet. Keeping a conversation going about something other than the toileting event helps diminish the shame and discomfort.

As far as falls go; having her crawl over to a solid piece of furniture like a sofa or bed and then using that as a ladder to assist in getting her off the floor can work better than trying to physically hoist her like this. Also, This video offers another helpful strategy. Getting her a gait belt can give you extra handholds for a more secure grip.