It became the "Women's Division" in some sense of that word in the 1970s. But I think it was not until sometime in the 1980s before it lost all organizational independence and became just another element of the General Board for Global Ministries.
I am sure that from the UMC women's point of view, the bishops wanted the financial stake that the Methodist women had built on their own. Prior to becoming absorbed by the GBGM the "Womens Division", on their own, had been able to fully fund all their own programs, salaries and benefits for their staff operations and built and owned their own 17 story office building in Manhatten.
Of course, by then, the Women's Division had already become a fully functioning element of the leftward drift of the church, as that office building was built across the street from the United Nations and houses the UMC mission to the UN, besides other UMC groups.
The UMC to me is another denomination in which, institutionally, "belief" and "faith" have metamorphed into nothing but the intellectual practice of a religious philosophy. I am sure that many today who are comfortable in today's UMC actually believe that if Jesus were alive today he'd be a Marxist.