Another word on indoor make-shift toilets:

If a family member is older, disabled, obese, otherwise challenged, bedside commodes are readily available in all sizes and adjustabilities, both new and used. These will be far safer and more comfortable for many people, including small children. There are even liners for the container that goes under the seat, so that they and contents can be easily discarded into a larger trash bag.

Try a thrift shop, yard sale, anyplace you can think of. Not hard to find, and would be a great help to many, including that young child you were just starting to potty train when shtf.