Wagtail
Horse servant
When I had sharers for my horses I drew up a written contract. It stipulated that payment was to be made monthly, in advance and that if they were ill or couldn't ride for any reason, then they would be offered an alternative day to make up for it, but there was no reduction in money they paid. This worked very well with several sharers over a number of years. They did not have to do any stable chores however.