Council of Elrond

How does one add sideboard cards during a game without the sideboard being the Fallen Wizard sideboard already in use?
If my opponent moves to a DC world region, how do I add my DCworld sideboard if the gccg FW sideboard is already used?


Background:
DC, dream card, rules on construction state a player can add his 10 card DC world sideboard if opponent moves to a DC world region.

My Position:
Right now, I make four variants of my resource deck and select the variant when my opponent announces his alignment.

hazards vs. hero with DCworld extra sideboard
hazards vs. hero with FW/Lord extra sideboard
hazards vs. minion with DCworld extra sideboard
hazards vs. minion with Balrog/Dragon sideboard.

What should I do if I encounter a fallen-wizard visiting a DC world region?
If I start the game with both FW/Lord & DC world sideboards in the gccg FW sideboard how can my opponent trust me?
Please let me know the steps to follow so if my opponent is either Balrog/Dragon/FW/Lord and moves to a DC region
that I can use the appropriate sideboard without slowing the game.

Thank you.

nope, we don't have that extra sideboard option in gccg yet. Nicolai is keeper of the gccg TODO file

Of course, if you know you're not playing against a FW (or Balrog, if vs. minion), then you could copy/paste the DC World sideboard in the decklist, simply substituting the anti-FW sideboard.

Thank you for the reply.
I was making deck building harder than it should.
The solution is to place the alignment sideboard in with the regular sideboard since you will know
the alignment of your opponent when you start play; the FW-sideboard in gccg holds the DCworld sideboard.
I think now I remember someone on gccg saying that.

Thus, I will make four variants of a deck:
vs. hero with DCworld in FW sb
vs. hero,FW/Lord with FWLord cards in sideboard and DCworld in FW sb
vs. minion with DCworld in FW sb
vs. minion,Balrog/Dragon with balrog/dragon cards in sideboard and DCworld in FW sb