When you’re connecting subitems from one board to subitems in another board (e.g., Team A subitems ↔ Team B subitems).
Steps:
Go to the board where you’ll set the automation.
In the Subitems view, add a Connect Boards column.
Choose the board whose subitems you want to connect to.
Enable “2-way sync.”
Then go to the other board, open its Subitems, and click “+ Add column → Copy parent columns.”
Select the connect column that was just created from the first board.
Set up the "Connect & Sync" automation using the connect column that was generated when you enables 2 way sync. In the automation setting page, choose subitems on both fields.
Video: “Creating Connect Columns for Subitem-to-Subitem Connections”