I have my own configuration for "OStim Romance" which introduce a temporary dialogue with any NPC you decide to romance. Maybe I should post my approach update in this board some day.
Generally I romance NPCs following some stages of vanilla quests.
For example I find it logical to romance Elisif only after the end of Civil War and Dragon Slayer quest.
I was thinking about this mod
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(because I think the voice acting is good) and how to integrate it with the vanilla character
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.
In my approach Margret will be Silvia Salvian the imperial agent of General Tulius.
After the end of the forsworn conspiracy she will displace to Castle Dour at Solitude where she will live at the highest quarters. Then after the end of the civil war, if you side with the imperials (I always do that) Silvia will be available as follower and you can romance her. Removing all the tedious and boring dialogues/flirts of the original mod.