How did I miss this???
What a wonderful, remarkable transformation!
Now Julie, obnoxious? Our Laila obnoxious??
When a kitten has needed such close, intensive care as Laila, they tend to bond fiercely with the person who has provided that care. They see anyone else as a threat to the special bond you share. It's good that Laila has also bonded with your boyfriend, as it shows she's able to get to know other people besides you.
The approach that your visitors need to take is similar to that of dealing with a cat who is frightened of humans. Have them sit on the floor, completely ignoring Laila. Then they sudenly find that they have a wand toy, ball or cat toy that they're playing with, having a great time. Laila will most likely want to join in the play. Make sure the person doesn't reach out to touch her or pick her up, just play with the toys. The toys can then be brought a little closer to the person, so Laila is physically a bit closer.
The playing is a good introduction and teaches Laila that your visitors are OK and actually fun to be with. The treat idea is a good one. Find something that is safe to give her that she likes such as tiny pieces of cheese, cooked chicken or a little full fat yoghurt on the tip of their finger and have them feed her these. Be careful of using too many commercial treats, as they may cause diarrhoea.
I love that pic of Laila pouncing on the camera - look at those pinky paws!