A MDIV dissertation on the topic of church amalgamation. You can read the whole article here: https://macsphere.mcmaster.ca/bitstream/11375/19587/1/Puddicombe_Michael_W._2013Feb_Masters..pdf

ABSTRACT
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It is a sad reality but there are more churches every year that find it increasingly difficult to maintain the ministry effectiveness that they employed in years gone by. These struggling congregations face the option of closing their doors, partnering with IV another church or agency, or merging with another church with the hopes of continuing a ministry presence in their community.

​The merging or amalgamation of churches has been an increasingly popular option that many congregations are exploring but amalgamations are hard work and can be doomed to failure ifthe congregations involved do not discover the underlying theological reason why their churches failed in the first place. Churches fail when they stop being engaged in the missio Dei. The missio Dei is God's mission in the world to establish his Kingdom "on earth as it is in heaven." The church is a community of people in mission for God.

Churches that are interested in amalgamation should consider following a model, like the one presented in this thesis, which focuses on understanding and fulfilling the mission of God within their context. 

A great MDIV dissertation on the topic of church amalgamation. You can find the full pdf file here: http://ir.lib.uwo.ca/cgi/viewcontent.cgi?referer=&httpsredir=1&article=5876&context=etd

​ABSTRACT

When church attendance declines, congregational amalgamation is often looked to as a solution. To that end, institutional church bodies responsible for ecclesiastical governance offer guidance literature as a means of shepherding congregations through this complex process. As it currently exists, however, such guidance literature on how to proceed with amalgamation focuses on practical matters, and neglects a theological dimension. The aim of this paper is to highlight this paucity of theological foundation in matters of church amalgamation, and posits that this engenders sub-optimal conditions for successful congregational amalgamation outcomes. It looks primarily to Friedrich Schleiermacher for theological insights that may be useful in times of turbulent transition. As one mechanism of cultural development in contemporary times, faith based institutions should engage with theological ideas and discourse deliberatively and explicitly as a foundation for exploration of such issues as identity and community formation.
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