disclaimer for fellow chaps showing up for free ride

[max lenz]

in some countries they are generally accepted as "extra crew" but as it is obvious problems would arise for next of skin of captain after a crash I would like to let them sign a disclaimer and make a remark on the loadsheet to be sure it will not be lost in case...
who can help with a waterproof wording?

[411A]

Normally noted as extra crew member or additional crew member...if you give details, may be able to help...maybe.