Using SumIf and CountIf across multiple tables or something else

I'm importing multiple purchase orders with any number of transactions for a larger project management workbook which works great. My challenge is with the multiple transactions across multiple purchase orders. Sumif and Countif works fine with one table but I'm not sure of the syntax across multiple tables (named ranges?). In addition, I need to identify and summarize any product on those purchase order tables that don't appear on the master. So I seem to be looking in two directions, one from the master list to the tables for items that match and second from the tables to the master list for items that don't match (and if not, should there be an additional table created listing those items?) Thaank you in advance for your insights!
Lou