Is it illegal for a teacher to stay on the same work permit after changing schools in Thailand?

The user inquires about the legality of a teacher retaining her work permit and visa after moving to a new school in Thailand. The community response indicates that it is legal to have multiple working places if permitted by the primary employer. The primary employer must add the new school as a secondary location on the work permit. If she wishes to change primary employers, she must address her visa and work permit situations through the relevant local immigration offices.