Thank you both for responding.
My Spanish example was incorrect; she does add a “th†at the end of gracias ("grathiath"). Casa is “cathaâ€. So the problem is occurring in both languages.
She receives positive feedback from native Spanish speakers in our area (Mexican decent), so there may be a general unfamiliarity with the “thâ€. (I claim total ignorance, as my Spanish (and pronunciation) is atrocious!:blushing:) I am not worried about her receiving positive reinforcement….She is not the type of kid to do something to please others.
She lowers her voice before the sound in either language, so the lisp isn’t glaring. (Before I called it to his attention, my husband hadn’t noticed it, but he admits it is there.) Otherwise she is exact in her pronunciations.
There is a limited amount doctors here would know or could do about it, so I am going to relax and just mention it to a pediatrician the next time we visit the States.