Do reservists have to provide orders when missing civilian work?

I was an officer in the RA, and never really dealt with reservists or the Nationals Guard. Now I have a Naval Reservist that tells me things like “my commanders called and said I have to get my well woman exam tomorrow” or “I have to go get vaccines because my unit called and said I must do it before the next drill”. Is this common? I ask because she is a remote employee, and I have complaints from my clients that she is hard to find, when she should be in the office 8-5 Monday through Friday. There was a day when I couldn’t find her at all, all day and she didn’t reply until the next day, stating her unit called her in. Does she have to provide orders to me when using her reserve status to get out of work?