It might be cool to start this up again. I'll start. And I'll start with an easy one since I don't know what level of tricks people expect.

Although you can only grant one medal per mission, there's nothing stopping you from calling the grant-medal sexp more than once per mission. The effect of this is to replace the previous medal with the new medal. This can be used with great effect to award the player different medals depending on how much extra work he does.
For example, there's a mission in Silent Threat: Reborn where if the player completes all his objectives, he gets the Distinguished Flying Cross medal. He is then permitted to return to base. However, if he stays in the area and continues to help out, his medal is changed to the Meritorious Unit. (He has another opportunity to earn the Distinguished Flying Cross later in the campaign, so he doesn't miss out on that one.)
Because the player could return to base at any time after the mission was done, there was no specific time where I could say, "Okay, the player is done; let's award either this medal or that medal." Awarding the first medal and then replacing it was the solution.

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