We’ve been discussing mergers here lately, especially between Unitarians, Universalists, and other denominations. But there’s another level to this discussion that ought to be acknowledged: local mergers. From time to time a UU church merges with a church from another congregation, sometimes resulting in novel combinations. Given the congregational polity of UUism, there’s nothing to prevent this from happening: each church has power over its own affairs. Nor is this a recent phenomenon: some local Unitarian and Universalist churches combined forces well before the American Unitarian Association and the Universalist Church of America consolidated into the Unitarian Universalist Association in 1961.
In fact, these local mergers are what led to the UUA in the first place. Raymond Hopkins, the first Executive Vice-President of the UUA, provided the plan for AUA and UCA combination that finally broke the years-long deadlock over the legal impossibility of merger. His own church was born from the consolidation of a Unitarian and Universalist church in the early 1950s, and the UUA was able to use that same model to get around the legal roadblocks on the denominational level. Without that insight from the local experience, the creation of the UUA would have been delayed even longer than it was, and therefore potentially might have never come about (one can wonder, for instance, if a merger would’ve happened if the black empowerment crisis of the late 1960s had occurred within the American Unitarian Association, rather than the UUA–consolidation with such a volatile, and financially precarious, denomination might’ve given the Universalists major second thoughts).
Today the most common local combinations are churches that are jointly affiliated with the Unitarian Universalist Association and the United Church of Christ. Even more interesting combinations also exist: for instance, All Souls Bethlehem in Brooklyn is a Unitarian-Universalist UCC Disciples of Christ church–that’s three for the price of one! It also weaves together the four strands that have historically most often figured in merger speculation: Unitarians, Universalists, Congregationalists, and the Christians.
Yet another possible item for this discussion is the fact that non-UU churches could join the Unitarian-Universalist denomination. For example, Philocrites mentions that an Ethical Culture congregation is considering becoming a UUA member. Ties between Ethical Culture and UUism have always been pretty healthy and the trend continues: for instance, Rev. Richard Nugent, a UU minister who has served many congregations, has been serving an interim term as leader of the Ethical Culture society in D.C.
Either of these could be the model for future mergers at the denominational level. For example, if individual Ethical Culture societies join the UUA and find it a positive experience, this could eventually lead the entire denomination to join. Likewise, if enough UU and UCC churches combine on the local level, eventually pressure might develop to merge them at the top as well as the grassroots level. This would recapitulate the Unitarian and Universalist experience to some degree, and there’s no reason to think that future developments in liberal religion will necessarily begin as top-down movement.
Transient and Permanent 
There’s one small snag to multi-denominational congregations joining the UUA post-1961: A UUA rule requires affiliating congregations to assign congregational assets to the UUA in the event that the congregation dissolves. See Rule III.3.5f. Congregations established prior to 1961 do not have this requirement, which may explain why most federated, united, or multi-denominational congregations predate the merger.
That’s interesting, I hadn’t noted that rule. That’s for bringing it to our attention.