Precompose the envelope layer, leaving all attributes in the Main Comp.
Open the precomp, add your stamp layer and position it where you want.
It’s now connected in the Main Comp.
By the way, 3d transforms, including rotation, are respected in a parent/child relationship as long as both layers have their 3d switches enabled.
And if you wanted, you could just pickwhip an expression linking the layers’ opacities. But that’s less flexible and more work than necessary for what you need.