@sk@utsukta.org mentioned in another thread that the way Hubzilla and threadiverse software handle group discussions is incompatible. It got me thinking about whether that is true. At its core both FEPs (171b and 1b12, respectively) rely on a central "distributor" node to send activities to recipients. @silverpill@mitra.social did further comparisons in thr text of 171b itself: Announce activity is used instead of Add. Conversation and related activities are synchronized between participants, but conversation backfilling mechanism is not specified. The questions here are: If threadiverse software federated out an Add in addition to Announce, would that satisfy basic synchronization (not backfill) requirements laid out by 171b? Is there any reason why Announce could not be used to facilitate private federated group discussions as well? Assuming visibility maintains scoped to addresses, I don't see any immediate reason why not...