Can my employer ask for documentation for a funeral?

I have been working for a school for 4 years. The last two years have been filled with harassment, discrimination, and retaliation. I have filed a grievance with my union and since then, I have been treated even worse than before. I have hired an attorney as well, but my job does not know that yet. A week ago, I had to leave town due to the death of my grandmother. Per our contract, I will get paid for bereavement time. However, my job doesn't want to pay me unless I provide them with documentation of the funeral. It does not stipulate in my union contract that I must provide documentation of the funeral. My grandmother had a rather unconventional service, as per her wishes, so there was no obituary published. I'm sure I can get some kind of documentation, but I am not going to go through the trouble unless I have to. I know that they are just trying to make my life difficult. Do I need to provide documentation if they do not specify that in my contract?