amalgamate
verb (used with object)
to mix or merge so as to make a combination; blend; unite; combine.
Used to describe an ongoing action or continuous state that was happening at a specific time in the past.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
While Europe was Balkanizing, the city fathers were amalgamating what become the five boroughs into Greater New York.
From New York Times ● Sep. 29, 2017