An interesting point to make and deserves better than my guessing.
I suspect that any declaration will be only a release or "blood chit" for the website.
Unenforceable, but will comply with US regulations. That said, I assume a declaration will have to identify the signatory who presumably is father of ...... or at least a responsible adult.
So an email might be acceptable, but only if "they" don't need a signature.
For serious bits of paper in this country, faxes and photocopies won't do, it has to be hard copy via snail mail!
If a signature is required, then it will have to be a document which has been signed before scanning and then treated as a "print" by the Fax facility on your PC.
Presumably you have a dial-up modem and this can be set up through Control Panel as another Fax) printer. A lot of these modems have software which will do this for you, but Windows has its own anyway.