They're all adorable!
With regards to stray/unsociable cats, we had success in the past with socializing them though it takes time.
If you haven't already I would spend a good half hour a day just being near(ish) them without encroaching too much on Mums personal space as it were. Maybe take a book to read and just sit, maybe put a nice snippet of food in-between you and mum.
Oh and give mum lots of squints whenever she looks at you, even turn your gaze away from her. (For those who are aware this is cat language for "I'm not a threat!")
This will help later when you need to get them all spayed
I'd love to take them all but it's too far and my own cat would probably have a fit

Best of luck with re-homing them though!
PS.... Horrible to mention, but get them tested for Feline Aids asap!