OK yeah. They quest completely keys off the idea that one of the two (Sven or Faendal) has a high relationship with Camilla based on what you did in the Lovely Letter.
Now, I'm not familiar with this "subterfuge" option you described. I don't think that's part of the Base Bethesda lovely letter quest. If you got that option from some other Mod and jumped the tracks of the Bethesda Quest then, yeah, no fix for that.
Also, what is this "Nexus" you speak of?
Ah, that does make sense Though I can't recall a mod I have that does that it does not have dialogue and is not vanilla, I assumed it was yours.
I'm keeping all my saves so... 4 hours lost of Legendary gameplay... ugh. Anyway thanks! great mod!
also, sarcasm doesn't translate well over text, so, on the very slim chance this was serious, just google skyrim nexus
Every single line of dialogue in this mod is voiced. If the NPC is talking to you and it is silent, you know you're not in this mod.
Anyways, checked the Skyrim Wiki - didn't see a "Use Subterfuge" option. I didn't think so or I would have accounted for that. Everything in Amorous Adventures keys off where a player should be based on where Bethesda says they should be.
/jk Nexus
Thanks!
The third way is definitely part of vanilla Skyrim, and I've done it myself on a few playthroughs. http://www.uesp.net/wiki/Skyrim:A_Lovely_Letter shows the possible path, check the last point in the notes section.