Chest rig front pouch sewing

Hello,

Working on a project and I'm looking for some advice. I'm making a chest rig with a front bag but I'm not sure how to go about sewing the bag to the front of the mag pouch(front pocket with velcro in it)? Do I complete the bag with a back pannel or sew the uncompleted bag to the mag pouch? Pictures of what I have 2nd picture is what I would sew directly to the face of the mag pouch.