If you talk to Delvin Mallory when you receive the quest of Promises to Keep, he will tell you you're playing a dangerous game and that the thieves guild will have nothing to do with this. I don't think it will make any difference for the quest tho.
If you talk to Delvin Mallory when you receive the quest of Promises to Keep, he will tell you you're playing a dangerous game and that the thieves guild will have nothing to do with this. I don't think it will make any difference for the quest tho.