Hello,
I feel like I should know this, but its been a while since I last went to Gen Con.

Say I have some friends (Hard to imagine I know). Say that one wants to do ALL the True Dungeon, and the other two want to try it but don't want to do more than 1 run.

I add all 3 main True Dungeon runs with all 4 of us, and mark the "Only get if ALL tickets are available" checkbox.

Wishlist processing time comes, I luck out and get say 2 of the runs with all 4 tickets. However, I only need all 4 tickets for 1 run, and 2 tickets for the other. 

I can, at the time of wishlist -> Shopping Cart, remove the unneeded 2 tickets from the one run, correct?

Thanks,
~Komori

Yes.

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​​​​​​​Alec Usticke, Fans of Gen Con Facebook Group

Once you submit your wishlist, it will show you what you have and what you did not get. You will have time, not much but some, to decide if that is what you want to get.