How do I charge for Lawn Care?

[Brad Crosby]

I currently have 2 renters that are moving out soon. The house they have been renting is under contract, and the sale should be finalizing on May 8. The situations is the lawn has grown incredibly wild with all the Spring rains we've been having, and I want to make sure it is still being maintained during the sale process in case the contract falls through, as well as a general courtesy to the new owners. 

Taking care of the lawn is addressed in my rental agreement, and the renters were aware when they signed in November that they would be responsible for this. They are still held to the agreement until the house sells (because they are defaulting on their contract which is what brought about the sale in the first place.) Therefore, I reached out to them to ask if they could mow, and they told me they had no means of doing it themselves. I asked if they would like me to find someone to mow it for a fee, and they agreed.

So this brings me to my question. I have cooperative renters, I have found someone that has agreed to mow on an every-other week basis until the home sells, and now I am just wondering what is the process for billing the tenants? 

I use Rentler.com to collect rent, and the only way to add additional fees on their website is by adding it onto the next month's rent. As it is April 10 now, I would have to charge for two mowings in April as well as 1-2 mowings in May, and add that onto May's rent. Then I could just refund them whatever amount they paid that did not get mowed in May (depending on when the house sells, which should be May 8.) I think if I explained this to them they'd be more than happy to go along with it, but I was wondering if there was a better way... Is there a special invoice or other form that I should be sending them to make it more official? Should I be requiring them to pay the servicer directly? Any ideas or advice is welcome, thanks!