As a peripheral war it is only represented, but you cannot fight there.
It is not clear how to allow combats between units of two countries not at war like Spain and France in that moment of the game, the same for Imperial units.
And if you allow that, then French units in case of victory could get into Germany from Mantua. Complicated issue.
Headquarter game designer of Battles For Spain, Ageod English Civil War, España:1936 and Thirty Years WarHQ website