From the various answers, it seems different concepts are mixed.
1. Copyright : usually the photographer holds the copyright of a photo he's made. Unless he was commissioned to take the photo(s) and the commission contract specifies the contractor holds the copyright.
2. (Personal) image right : the model(s) representedin the photo have a right to " privacy " which prevents others from publishing her / his / their "image" without her / his / their consent. Usually when the model is paid she / he signs a "model release" authorizing the photographer to sell the photo(s) for publication. Model releases can contain various clauses limiting the use / geographical distribution / type of distribution.
3. Photographing minors : it is highly recommended to obtain a parental authorization from BOTH parents / tutors to phootgraph an underage model. Likewise if there is a model release involved, it should be signed by the parents / tutors ( BOTH ! It could become nasty in case of divorce otherwise ).
When no money is involved as is the case here, I use a TFCD ( time for CD ) or TFP ( Time for print agreement ) on top of the model release. It is a 2-way contract where the model and the photographer acknowledge the shoot was done for mutual interest of promoting's one activities as model / photographer. I have designed mine in a two column layout, one column for photog, the other for the model.
And both parties have equivalent rights and obligations. Both parties acknowledge the agreement covers non profit use ( i.e. promotion use of the created photos ) and that any other use requires a further agreement and compensation.