Brendan has threatened to deadlock the Universal part of the dynasty over Veto conditions. I think it would be more productive and on-theme to negotiate than to merely threaten. And that requires the veto conditions to all be explicitly spelled out.

This is the starting point, after input from Clucky. The Player should Veto any Treaty change that attempts to:
* add or remove Signatories from another Treaty, except as mediated by Universal rules
* Restrict the actions of non-Signatories, beyond not being able to act as Signatories
* avoid the requirement that the Player always be a Signatory
* Make substantial modifications to another Treaty, such that it effectively becomes a different Treaty. Trivial modifications are now permitted. (thanks, Clucky)
* Enable arbitrary rules modifications, as that would indirectly allow it to mess with Signatories.
* Prevent the Player from vetoing proposed treaties that violate any of these bullet points

In each case where “another Treaty” appears in those requirements, parent rules are nonetheless permitted to mess with their subrules.

The following workarounds are expressly permitted:
* Treaties may have terms specific to mutual Signatories with other Treaties, for example by modifying variables defined in the other Treaty.
* Treaties may declare the Player and other Signatories as second-class Signatories who may not take certain actions.