I have multiple data sources that have city, state and country information.
Example -
Source 1:
ID      City        State       Country
12345   New York    New York    USA
12344   Cebu City               PHL
12232   Bengaluru   Karnataka   IND
Source 2:
ID      City    State    Country
12345   Dallas  Texas    USA
12344   London           UK
I would like to create a filter to show drill down option into country, state and city using both the databases. I cannot combine the source due to few sourcing issues. Not sure if a set can be created like union of the columns from the data sources to be able to show a filter that will have values from all the data sources.
Like..
Country = USA, PHL, IND, UK and then filter state and city and so on. 
Can someone please advise how I can achieve this? The city, state and country columns are dynamic in my data sources