Just another perspective. I clicked into your post with interest. Working in schools can be difficult at the best of times and I know this from experience.
I note this is a very young but gifted therapist and I wondered whether it might be useful to explore with her why or on what basis she feels underused and undervalued and what she might be able to do ( if anything ) to change this state of affairs.e.g. Is she tapping into perceived need, does she need to network more/ educate more, is this a school which has lost heart or faith in speech therapy because resources were previously unavailable and they have had to manage without. If she is gifted and loves what she does, these aspects are challenging. She may have to prove her effectiveness and demonstrate her commitment. If she can and circumstances permit, this can be extremely rewarding.