I so agree.  The difference here is that they were friends beyond school AND were in the same neighborhood.  The birthday girls' mother should have had the tact to call and explain this or find a way to include.  "Desperate" is really not part of this at all.  This was not handled well and  calling the mother to give her a chance to explain takes a bit of courage.   She did it gently, showing empathy with the difficulty of the situation, and it took grace to do...