The function of the FragmentsUsers table is to construct a dream's contributory base. There is no table that holds meta-data - such as a users' contributory weight to the dream. Demarkation for the user that randomizes any given dream is done via the UsersDreams table. However the lineage of this contribution is not recorded, thus a dream whose contributors are users A,B,C may be a 30th generation mix by user D, but never reference who else was involved in the dreams generations besides user D.
It is proposed here that any question of the origin of forms present in a fragment can be best investigated through the users that have claimed those fragments. Whether a form present in a fragment has stirred within any given individual (user or not) can be considered a form of quantum state. The form-state coheres when an individual announces the presence of the form within them. An individual's dreams likely represent form that move within them, and rendering these dreams becomes a method to observe forms of the world (at least those that are within the reach of collective or individual human awareness).
In terms of this system an individual must be a user in order to render these forms - and doing so construes them to those forms via the dream fragments they contribute. Associations delineated in FragmentsUsers is the only construct of individuality built into the system; however, it is reasonable that the association exists only to lay a foundation for exploring the role of social, cultural and environmental structures in the realization of form.
There is no explicit maintenance of dream creation lineage. In the truest maintenance of heritage multi-generation dreams would have increasingly lengthy weight lists, culminating the total of dream generators - or would record these ancestor in a separate history table. Perhaps most relevant of an issue would be that the contribution of a fragment would have equal weight to that of the organization / generation of a dream - and if not, how the relative weights would be determined within the system.