Pass Index Masks for Grease pencil

One issue we have with the Layer masks is that you have to add each individual layer in the pop up list. If you have alot of layers it's almost impossible.

But what if there were a option in the layer mask menu And/Or a modifier for Grease pencil that let you select a layer to mask things to , then set a "Pass Index" for the layers you want masked ? That way you can just go the the layers you need masked and change it to the same Pass index. Similar to how you would other modifiers. " Time offset " for example.

Also The modifier's Base function could be the same as the normal Mask modifier