Powys council is considering closing Gwernyfed and Brecon schools to create a single school and doing the same at Llandrindod and Builth Wells schools.
The changes could be put in place for the start of the September 2017 term but hundreds of parents and pupils have aired their concerns.
If approved, the changes could cut costs and tackle surplus places.
Opponents are concerned about the distance some will have to travel to get to the next nearest school.
The council started the consultation in April and extended it from May to June.
A consultation on controversial plans about the future of four Powys secondary schools closes on Wednesday.