I am digging in to the latest PD7 and Effects but I dont see one which will do what I want.

I would like to take the uppermost PIP layer (or layers) and make them have a specific level of transparency so that the underlayer (another PIP or Video) bleeds through just like you would do with Photoshop layers.

It seems an obvious proposition but I cant seem to get it done.
I tried reducing the brightness of a PIP and saving it and then using a gray chroma-key to make the Video layer bleed thru but its klutzy and not at all what I wanted.

Any help out there?

If you can't solve the problem - Change the problem