Adding additional data to Union table

[mterry]

I have a table, which is really a single column, that combines the distinct vehicle number values from several data sources as shown in the snip. What I'm hoping to do now as an additional step, is to add a second column that can flag whether or not the vehicle number has occurred in the fleet_revenue_analysis table within the past 12 months? Is it possible to add that data in the same step, or perhaps as a second additional step?

[lbendlin]

You can use ADDCOLUMNS or SUMMARIZECOLUMNS or SUMMARIZE - there are many more options to do that BEFORE you do Union.  All Union cares about is that it's the same number of columns. It is your responsibility to provide them in the right order and with the right type.