Stop adults from purchasing using family sharing
I am the main account holder, and therefore it uses my Credit Card. I wish to prevent other Adults in my Family Group From making purchases without my knowledge or authorisation. I believe you can ask children to request authorisation but any adult can just buy without restriction. If this is not possible then Apple needs to seriously fix this and allow adults to purchase with their own cards and restrict minors only.
iMac (21.5-inch, Late 2013), OS X Yosemite (10.10.1)