To make it easy to manage your work across boards, we made it easy to view your boards as one board.
The first step to achieve this is to create a Board group, as shown in this article.
Then, in the board view, you will see all boards in the same screen. Clicking the "combine boards" button will merge temporarily all lists with the same titles as if all cards were part of the same board.
When cards are moved between lists, we check the original board to make sure there is a list on this board with the same title. If there is no list you will get a pop-up to ask you to move, copy or mirror the card to the new board.
On the other hand, when cards are already combined, clicking "Split boards" will make you see the boards separate again.