How would this work for combine multiple different tables though? The way I'm reading it, each set would need it's own stored procedure, right? For instance, the 3 examples above are of the full sets that need to be combined. Each combination would be a separate join in SAS currently, as the groups themselves have nothing in common.

I'm also a bit confused, as it looks like it's modifying the union function: Is that only when that function is running or is that a permanant thing?