Unless someone else is entitled to claim the Birth Certificate that you hold in your possession/pocket, then you would be the sole party authorised to act and/or administrate matters for that person...
That is how you can assume the role as sole authorised administrator for the person...unless they handed that same BC out to more than one man/woman :D
Printed copy · Anthology Volume 6, page 377Printed copy from The Tender For Law Anthology, Volume 6, page 377 (printed 13 June 2014). Added by this site; not part of the Facebook export.