Ok, So let's say Katniss didn't win the games and The Quell was the same, and there are no girl victors in 12, how would they pick a girl tribute from the pool of victors?

Actuallly, what i think happened is they made the quell like that so that it was a way to kill Katniss. I don't think they thought of this quell until they decided they needed to kill Katniss. Of course they didnt expect haymitch to save everyone....

They probably only picked the tributes-from-pool envelope because there were only three to pick from.
If it were picked after Katniss was killed, however, they would probably reap a female the normal way

they would just reap girls and pick between Haymich and Peeta

They'd pick the closest female to Haymitch (and/or Peeta if he won), or they would just do a draw from the Reaping balls

I don't know!! I guess they would just have two boys!!

Its simple. They cant so Haymitch and Peeta would have to go. Also that would be very sad...

Ok, well in the book they kind of hinted that that wasn't the original quell. That president snow *spit on ground* changed it to kill katniss. So think that if she didn't win, if the berries didn't happen, then that would NOT be the Quell. Plus dont you think its a bit suspicious that it said "to show even the strongest cannot defy the capitol" (or whatever It was) JUST when theyre trying to prevent uprisings? Seems dodgy to me . . . But anyway, if I am wrong . . . Then I guess D12 would be screwed! ;)

pick a random girl

They had made up the quell to punish Katniss. I'm actually curious what the original Quell was supposed to be.

That's not possible because Katniss said that they made it that way so that there was a better chance of her dying

uhh...probably they would reap some random girl

they would pick another female from another district

Probably pick a citizen from district 12

2 options:

1) Reap from the male victors
2) Reap a tribute the normal way

Snow probably changed the envelope.

I actually thought about this a long time ago. Even if the quell was made to get at Katniss, there are 11 other districts in the game, and they said that the trivutes usually win. Even after 75 years I find it unlikely that every district would have a girl and boy winner, let alone multiple ones to choose from. It is one of those things that I had to just go with, because I dont want it to mess with my enjoyment of the books.

To actually answer your question though, the only thing I can figure is that if a district didnt have a winner from one of the genders then they just wouldnt have a tribute from that gender in the games. The whole point of this quell was supposedly to show that even the strongest arent safe, so it wouldnt make sense to pick someone who hasnt been in the games before.

They only picked that way because they wanted katniss dead so they made sure that she got back in the games by pretending that's what the seventy fifth hunger games was suppose to be like

no

The Quell was changed so that Katniss could have an another opportunity to be killed.
If she had died the the quell will had been the same:
1 female tribute and 1 male tribute
as always but more important, as the past one in which Haymitch participated

They decided after Katniss rebelled to try to kill her. I don't think it would have been the same Quell if Katniss wasn't chosen.

If that particular Quell option was chosen when there wasn't a female victor for one district, the Capitol could throw in two male victors from that district instead, or choose one of the female relatives of a victor. But honestly I think they screen the Quell options and only choose one which is feasible at the time.

We'll if Katniss wasn't there they would not have had to pick from the victors,because they devised that plan especially to kill Katniss. President Snow changed the rules so that all the victors could off themselves!

They'd find a way.