Ok, this is gross, but need some of you smart people out there to make a suggestion. Mother has started having a BM in bed at AL. Ideas?

My tiny, sweet, humble mother has advance dementia and has started to have a BM in her bed at AL before the caregivers get her up. Then she proceeds to pull off her depends and make a real mess with the contents. UGH.. they want me to buy full bed sized disposable pads - which are hard to find and cost $4.00 a piece! I know she’s making a lot of extra work for them, but there has to be a less expensive solution. I bought 2 more of the washable ones, but they want to be able to just throw the mess out.