Roof panel insulation in between panels

[chewychevy67]

Ok so I am reworking my cab right now and I removed my inner panels and am adding one with the headliner holes in it. Now once I removed mine I thought I would be able to remove the insulation/sound deadner pad from mine to the panel I was installing after I cleaned up and seal it. Well it does not come off in 1 piece. So what can I use here to replace it? I'm assuming nobody makes this piece. I'm assuming it can not be thicker than what was there. What have you used here if you have done any rof repair. Pic is not my truck. It just shows the pad I'm referring to.