Pass Index to GP v3 Groups

Hi folks, I'm working with both 4.3.0 and 4.3.1 RC versions. I'm finding the GP groups very useful but not as useful as I think they can be. The most important thing for me is to have a Relations tab when a Group is selected so you can manage the Pass Index at group level and not necessarily layer by layer, as we can't "Copy value to selected" in that specific attribute (¿because we can't select several layers in the Layers tab?). Maybe there's some workaround I'm missing but it would be nice to have this handy option. Best, Juan