She does not have to sit with them because they subpoena'd her. Wouldn't that make her their adversary? And a phone call does not make a subpoena.
But this seems to be a last minute ploy by your X to drop things. Only a jerk would upset his child like this (I thought of a few different words but didn't thing the mods would let them fly).
If she goes, it's on him Queenie. Sometimes we can't protect them any longer. Sometimes it allows them to see things the way they really are. Maybe in the morning you could ask your A if your daughter can stay in the lobby until testify time and then let her leave.
