Good question. I also want to know.
If you want the place where you put the flowers cleaned or cleared.... you have to put in a work order with the office. Which I find ridiculous since it should be part of maintaining you loved ones gravesite.
I honestly doubt that they will do anything on Thursday due to the fact that during thanks giving the entire world stops simply because everyone wants to party with their friends and relatives. But it wouldn't hurt to go directly to the office and speak to someone at the front counter or call them to ask them if in fact someone will be working on Thursday. Good luck!
Thanks! Your answer is awaiting moderation.