In the rule The Grid, make the following changes:

Change “Re-draw the board to match the Grid Size” to “Increment or Decrement the Grid, as needed, to make the Grid match the Grid Size”
Change “Set each cell on the board to blank” to “Set each cell on the board that does not contain a Building to blank”.
To the paragraph that starts “When the Grid is Decremented”, add the following at the end of the paragraph:

When the Grid is Decremented, any Symbols, Buildings or other gamestate entities that occupied one of the cells that have been removed ceases to occupy any Cell on the Grid.

Whenever the Grid is Incremented or Decremented, the XY references to each remaining Cell on the Grid are updated as per the third paragraph of this rule, and any Symbols, Buildings or other gamestate entities on the Grid whose location was being tracked by use of such references have their references updated.