Querying Multiple Tables without using multiple connections

You can actually set the target field dynamically using a pipeline parameter, but maybe was hard to find in the documentation.

Here is an example that I think will get you on the right track. In this example, the Group By N snap is used like you mention. I set the value to the pipeline parameter _TABLE, which has the value my-table. To do so, use the syntax $[(<pipe param>)] where <pipe param> is the pipeline parameter you want to use, so in this case $[(_TABLE)]. In the preview data, you can see that all documents were aggregated under the value my-table.