I would allow her to do what she wants
she certainly isnt in the age where she can train thro pain and damage herself = she think she is doing too much she will stop
there is virtually no data on this and it is probably safe
( alk phos may be raised but we couldbbnt work out if alk phos was raised in children anyway)
https://www.stanfordchildrens.org/en/topic/default?id=sports-injury-statistics-90-P02787
[sports injuries in children are mainly head injuries after contact]
there was a thirteen year old turning in decent times for half marathons and marathons - and the commentator said "the main problem actually is that she will become bored with the amount of time it takes up training..."