Table Join queries sources again

Hello.

I have two queries, one web service call and one a normal select from a sql db.

When I introduce a third query to join these two, the new query calls the webservice and db again. 

I was hoping it would use the resultsets of the first 2 queries to do the join.

Is there a way in Power Query to join the "already fetched" datasets. Hope that makes sense.

I can't use DAX as once the tables are joined I have to go back to the webservice to do another call based on the result of the join.

Thanks