I think you're wasting your time. If it starts to sag in one area, the rest of it will eventually start to sag too. One way or another the headliner is coming down.Oh ok. Then I'm considering slicing that fabric in the area that'll be hidden by that front trim piece. Spraying some headliner adhesive or fabric adhesive and hoping it sticks. Don't really have much to lose. And the cut I make will be hidden.