Once a week in a midtown Manhattan hotel, dozens of Girl Scouts gather in a spare room made homey by string lights and children’s drawings. As government officials debate how to handle the influx of new arrivals, the Girl Scouts — whose Troop 6000 has served kids who live in the shelter system since 2017 — are quietly welcoming hundreds of the city’s youngest new residents with the support of donations. With anti-immigrant rhetoric on the rise and a contentious election ahead, some donors see the Girl Scouts as wading too readily into politically controversial waters.