The concept is that you create one sheet for each model. Convert the sheet as a JSON and create instance out of this JSON
A quick tutorial to change your google sheet as a JSON
The json url should look like:
https://spreadsheets.google.com/feeds/list/keyOfTheGoogleSheet/public/values.alt=json
You want to reference two times the same model in a table (user_1 / user_2)
t.references :item, foreign_key: { to_table: :items }