Support all guests to sign Rental Agreement

Our vacation rental permit requires all adult guests to sign a rental agreement.  We have it manually working in OwnerRez using custom fields and sending the link to each email we collect in the custom fields - but it is not formally supported and has a couple of challenges.  There have been recent form updates in the rental agreement which confuses guests to override the information that the booker initially fills in.  I would like to see a more formal approach to handle multiple renters being able to sign the rental agreement including automated way to send to multiple guests, disabling the bookers contact information so other guests updating their information do not override other details, etc.