A Vermont church that houses a program for preschool children is facing some opposition from parents over its proposal to act as a homeless shelter in the winter. Burlington’s Development Review Board approved a zoning permit for the shelter last month at the North Avenue Alliance Church. The paperwork needs to be signed and then held through a 30-day appeal period. Organizations that work with the homeless told parents at a meeting Wednesday that people would be screened and bused to the church’s gym hours after the preschool, which uses the gym, closed. But some parents felt uncomfortable with the idea.