How to connect materials across the field when importing?

Hello! My wife keeps a record of family expenses in Microsoft Access, I want to transfer her workplace to Drupal 8. In fact, the whole task comes down to transferring three Access tables to MySQL. This can be done using the feeds module. But problemma occurs when data is bound.

Specifically. There are tables: 1 – category of goods; 2 – list of stores; 3 – purchase.
The first two tables are enough to import as they are. But how to make the third table add links to the entities (fields) of the first two?

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/37/feed