Cryptomatte / AOVs questions - help

[Pavlov]

Hi all,
in Octane for Lw the only Cryptomatte channel that seems to work is material pin node. Other ones are unreliable or create too many photoshop layers.

Questions are:
1 - is there a pratical way to *group* materials or objects so i get less crypto layers ? I.e. if i have an instanced grass i would love to get a single mask out of it, not 30 masks for each single material in the ecosystem.
2 - Putting Cryptomatte aside, in Corona for MAX i can select the BW masks to output and even group objects together. Is there a pratical way to chose which object should go in each mask using other techniques which are not cryptomatte (layers, baking groups, etc) ? BTW the default Object ID and Material ID masks are useless since the selection is not precise at all.

Thanks in advance,
Paolo