I know that another mod exists called "Save Mission" by jc2, which ultimately has all the same functions as my mod. I created this mod from scratch, using "Save Mission" as inspiration, so it has all different dialogue for the player and NPCs. The outcome is the same, but the events unfold differently. I feel that these differences, as well as the absence of a few bugs that are present in Save Mission v1.5a, mean that these mods both have merit. You may enjoy jc2's "Save Mission" much more than this mod, so I'd suggest trying both out and keeping the one you like better (you can't install them both at the same time).
EDIT: Make sure you have v1.2 of the mod, as it improves the dialogue choices and fixes a bug that usually prevents you from killing Mission. Even though this mod is about keeping her alive, it's still good to have the option to kill her as normal.