Multiboard Map with 1 chosen at start, the others fixed

Hello wonderful developers !

In module design, when creating a multiboard map, we can only set all the boards at design time.
While in a single board map, the choice is proposed at game start.

Would it be possible to add the option to let some of the multiple boards chosen at start time, while some others are fixed ?
Like : a 3x3 grid made of 8 permanent boards on the borders, and only the middle one is proposed at game start ?

The workaround today is to create huge board images made of both borders and playground, leading to heavy modules.
Or to make the playground a piece chosen at start, leading to the difficulty of edition when adding some grids as the image is not visible.