I have 2-3 employees on Trello.
We are currently on the Free plan. I have setup separate boards for sales and vendor rates. To keep track of project costs and profitability, I attach the particular vendor rate card to a sales card and connect both.
But, I don't want the employee on the Sales board to be able to browse and open the vendor rate card on the Vendors board by clicking the connected card. And vice versa for the employee on the Vendors board.
I have tried looking for this functionality on Trello, but cannot figure out the minimum plan where this can be achieved.