How can you update the column_values in an item retrieved via a connect_boards column

We are using CRM, and have an “Account” column on the “Deals” board that is a connect_board column type. using the API, I want to update a column on the first linked_item (i.e. the Account for the deal) when that Account gets created in an external system. I’m struggling to figure out how I structure the “columnValues” for this mutation, any suggestions? If I could get the boardId for the linked item, then it would be easy, but since I access the item through the connected column, I don’t have a boardId to use - can I update the Account column through the linked_items, or do I need to do something else?