Steve Lowell says he took the phone call back in early August; he doesn’t recall the exact date. Everything else, though, he remembers quite clearly. That’s because on the other end of the line was Paul Mina, president and CEO of the United Way of Tri County, who asked for a moment of Lowell’s time — and used it to get a whole lot more than that. Mina was calling Lowell, president and CEO of Monson Savings Bank, and chairman of the board of the United Way of Pioneer Valley (UWPV), with a proposition of sorts, a unique partnership that has many potential — and, in some cases, already real — benefits for both United Ways. That partnership comes in the form of a management agreement (two and a half years in length) whereby UWTC, as it’s called, will essentially share a CEO (Mina) with UWPV and handle backroom operations — bookkeeping, marketing, and others — for this region’s United Way for a percentage of the funds raised during its annual campaign.