Yechaveh Da’as 2:29
Mutar and considered a seudas mitzvah. No difference in this respect between boy and girl upon reaching age of chiyuv in mitzvos. Also, that Ben Ish Chai would consider it a seudas mitzvah if it was a thing that people did (which they did not do at his time).
Sridei Eish 2:39 or 3:93 depending on edition
Thinks it’s a good idea similar to reasons for needing chinuch banos nowadays (in fact mentions Bais Yaakov by name). Agrees with Rav Moshe (by name) that it should not be done in shul. Says that it depends on the motivation (lesheim shomayim vs copying the minim as he puts it). Questions why some asser it based on emotion rather than halachic arguments (evidently there was a Coffee Room back then as well).