This is a pretty confusing issue and the worst case is what happened to both the men and women in 2000 - the winner of the trials didn't have the "A" qualifier. The trials winner always goes the the Olympics.
Now, if Deena, Marla and Milena remain the only three to have "A" qualifiers, they will all go if one of them wins the trials. So, if Deena wins, Marla is 10th and Milena is 15th and nobody else has run under 2:32, the three of them are off to the Olympics. There is a small window after the trials and before the Olympics where the 2nd and 3rd place finisher can try for another sub 2:32. Then they would secure their spot in the Olympics.
Now, if someone could answer these questions - Do you have to run the trials to go to the Olympics? If Deena, Marla and Milena have their "A" qualifiers and nobody else runs sub 2:32 before the window is closed, can they go to the Olympics if they missed the trials? Can someone that finished out of the top three at the trials run another marathon and go to the Olympics if they run a sub 2:32 after the trials? (Assuming 2nd and 3rd place don't have an "A")
Wouldn't it be easier just to have three women run really fast at the trials?