AW.............if your girl is ok with it, yes - absolutely do it. You will see quite a bump. I added my sister to 2 of of my AMEX accounts and she realized an increase of 56 points.
You want to be added to a tl with a long history, no lates, and with a high cl. If she has an account(s) like that and she is willing to add you - it's a winner for you.
I wouldn't worry about FICO '08. By the time it kicks in (if ever) we'll all be old and gray.