In family sharing, can I block child purchases if they don't have enough store credit to cover it?

[iMore Question]

In family sharing, can I block child purchases if they don't have enough store credit to cover it

I want my daughter to be able to buy on her own without me have to approve every purchase when she buys her own iTunes gift card, but I want her not to be able to accidentally go over it and have it charge my credit card.

 

[warcraftWidow]

That is not an existing feature.