Brief Thoughts: Charters as Parties
A brief exchange with the luminaries of Phlox's Glog Server this day has left me with this idea: Define the party by a concrete artefact: The Charter.
The Charter is a literal book carried by the party at all times. It may be cursed: Its durability is supranatural and if lost, it ever returns to its subjects while they yet live. It is part piratical Article of Agreement, part corporate charter, part ledger, and part campaign journal or Company annals. Perhaps successful venturers will pay to preserve themselves more fully in it, as incunabuli.
Whoever is written in the Charter is a member of the party. Obligations are absolutely transferable. You can find a Charter in a ditch, surrounded by dead members, write your name in it and - like that - you are legally entitled to party assets and subject to party obligations.
Society understands this. Peasants and ruler alike are not discomfited to find the knights charged with defending a march wear the same arms, but are completely different faces - perhaps like the Emblem Men of Vance's Planet of Adventure. Enmities are inherited, as are friendships. Curses and spiritual patronage are inheritable.
Every party has an Annalist charged with recording their doings. Knowledge seeps into members even beyond what they read. I can not say if the annals are legible to non-members: If they are, members nevertheless come to know what in the annals is plainly stated, what is edited, and what is flatly contrary to what is written.
Parties may find old charters in their journeys, or capture them from annihilated foes. They could 'split' - some members renouncing membership to gain it in the new, or revivify the other paty by finding enrolees.
The practical use of this is maintaining continuity even with high casualty games. Thus, in case of a TPK, the players could immediately resume years later when new members find the Charter and enroll. Investments may have gone bad, associates died, and the political situation may have changed, but the new party isn't quite starting from zero.