Angelina I personally think the idea is ok, but I don't think it's possible without the parents noticing
Except that the box in question is supposed to stay closed.
She will not be able to get so much attention from parents.
So as long as there is an identical padlock with the corresponding number it will not arouse any particular suspicion.
While belt locks can be checked daily.
The parents have a permanent visual on the belt but not on the box.
The attention paid to this box will be much lower than the inspection of the belt itself.
Moreover if the box has not moved for two years the attention of parents will inevitably decreased compared to it.