I have spent the better part of the day dealing with updating and managing Group Fields via Workflow and I'm exhausted. I already have one workflow that can change a value with a script based on an answer post I found. Not the best way but it works. the issue today was the fact that A user can add a group field and because I can't use default values in these (tried and anytime workflow added one values, it would mess up the order and just made it worse, so I apply values for all fields myself in a workflow to ensure the groups are correct) a user will leave some values blank. If you have blank values in a group field, the SDK script that grabs the collection fails with an error.
I found this post, https://answers.laserfiche.com/questions/127695/workflow-assign-field-value-add-null-fields-to-field-group#127740 and Miruna suggests rebuilding multivalue tokens and then applying the all once to get the groups to be correct. Well, most of the day was dedicated to building a workflow to identify when there are blank values and then trying to add default values to the correct location without changing the existing values.
Anyway, I guess this is turning into a feature request. We NEED a native Workflow activity that can interact with these values based on their index locations. Something that I could easily append values to certain groups based on the value of an index number.