Worried about Bartender

Hi All! I am getting married June 5th and love my future MIL, but at times she can be, well unreliable. She manages a bar and she said someone who works for her (who she is also good friends with) could be our bartender.


A couple months ago my FH asked who she recommended the to bartend and she said she would. The bar she works at currently is where we were ordering our kegs from and when we were talking to the owner and mentioned who was bartending the owner said oh she’s been off working for me because she hurt her back really bad...
I had my FH text her again and no response from her... this is now a week later. FH checked with his mom and his mom said oh she’s still planning on doing it, if this is the case why wouldn’t she respond. I am not sure if MIL reconfirmed or is just assuming. She often says what we want to hear. I don’t want to hurt my fiancé’s feelings by saying that his mom is unreliable but I don’t want to be out a bartender on my wedding
Any advice? Thanks!