How to display two boards at Game start

The C&C Ancients module has the main map and a side board displayed at game start. The side board contains the card deck, etc.
I would like to do a similar thing. I have a main board and a side board but when the game starts you are prompted for one of the boards, I want both displayed at once.

The designers documentation shows:

Select Default Board Setup: Click to choose a default set of boards. When a default has been set, the dialog will not
be shown to players when a new game is begun. Instead, the game will always be started with the boards you select. If
you click this button and then clear the boards, then dialog will again be shown at the start of each game.

I was expecting to be able to say I want two boards as the default but can’t find a setting for it.

Any help would be appreciated. Thanks.

Easiest way is have a map window that isn’t the Main Map window, and uncheck the box “include toolbar button to show/hide”. The extra map window will also be open when the module is started.