That might be possible, but I think Anavex will file first and have to file separately for Adult and Paediatric Rett. Whether there is any advantage for other indications depends on how the trial readouts for them are spaced.
In other words the key is that each indication require a trial, put these can likely be limited to P3 trials in related indications and age groups where safety is already proven in P2 studies.
A Type 9 NDA allows a sponsor to submit an NDA for a new indication or claim for a drug product while that drug product is currently being reviewed under a different original NDA (the ?parent NDA”), and the applicant does not intend to market this drug product under the separate NDA after approval. A Type 9 NDA can be submitted on the same day as the original NDA or months later. After approval of one of the NDAs and regardless of which was submitted first, the NDA still under review will be reclassified as a Type 9 NDA. After approval of the Type 9 NDA, it will be reclassified as a supplement to the NDA approved first, and the Type 9 NDA will be administratively closed.