I'm really having trouble here. I'm using UFO and try as I might I can't get Delphine to recruit anyone but Faendal (my first follower). I really want Borgakh And Illia to become Blades, but nope, Delphine seems to be fixated on Faendal. I've even tried to dismiss all my other followers then talked to Delphine, but then I don't get the recruiting option in the dialogue box! Talk about the woman having the hots for the elf! Anyone got any ideas how to solve this?

No one able to give me a console command to bring up the dialogue with Delphine telling her I've brought a recruit?

You have to recruit the companions one at a time. Dismiss all but one, recruit him, then go get the next one, and so on until all of your companions are in the Blades (or the 3 if not using an additional Blades mod).

I tried all that. I can only guess that UFO has caused that quest to form some sort of "queue" in the game memory, with the first follower I ever hired being first in line, whether they're still hired or not. I even dismissed EVERYONE (including Faendal) except for the follower I wanted to join The Blades, but the conversation with Delphine just reacted by not including the dialogue for telling Delphine that I have a new recruit for her.

I have the same issue, but not with all characters. I have UFO and, ordinarily, so long as I dismiss any companion and then recruit the one I want to become a Blade she will accept them so long as a bring them one at a time. However, with my latest character, I brought Mjoll to her with no other followers and got no dialogue. I have a save just before getting the recruitment quest, so I reloaded that and tried Uthegred the Unbroken with the same result. I tried a the console command to reset the quest and Delphine administered the oath but apparently to the air and not to the follower I brought. I have tried this with and without the unofficial skyrim patch. I have not tried it with UFO disabled. I also have the My Home is your Home mod and all my dismissed followers are at the homes they have been assigned. With one character, I apparently had failed to dismiss a follower who was waiting in her home. When I brought the intended recruit, Delphine actually left Sky Haven temple and found that recruit. I wish I could figure out why it works sometimes and not others and I really do not want to disable UFO just to do that quest.