Declaratively build merge syntax for each selected row in a table?

I’m looking to update a text field on one model (New Conga Template) with the values from same field on all selected rows of another model (Conga Templates) separate by commas.

Our use case is we have a skuid page for submitting a new Conga Template request. We want users to be able to choose from existing Conga Templates to list in the new template’s Template Group field. Template Group is a text field that reads multiple values separated by commas, e.g. Internal Template, External Templates, Community Templates, etc.

I’ve built a popup that has a table with an aggregate model of existing Conga Templates grouped by Template Group.

I’d like to build a Mass Action that updates the Template Group field on my New Template model with a comma-separate list of the Template Group values from each selected row in the table.

I know with child records you could do something like {{#Child__r.records}}{{SomeField__c}}, {{/Child__r.records}} to list all the values for all child records.

So really two questions:

  1. is there a way to do this with non-child records, e.g. does it work to do {{#$}}{{SomeField__c}}{{/$}}

  2. is there a way in merge syntax to limit what is being pulled into the merge to only those rows that have been selected? like maybe {{#selectedrows}}{{SomeField__c}}{{/selectedrows}}?