ok i just got in s&d bout half hour ago but nt sure how proper,but wen attemted again i coudnt master it lol.so here wat i did i think,
my friend invited me to private match,
then i went to playercard edit n hoverd over save n exit,
then he loaded a file share up (s&d)then changed to ct,
but wen he changed my screen went black with cod loading at bottom right,
wen it loaded i was in cbt with s&d loaded,
i tried again but with no joy,
the other thing is wen we was in private match another friend joined and got took with us,
but wen i ended up in cbt s&d the 3rd friend was in with me but the one changing to bt got kicked.

hope this can throw some light to pepole who trying to figure it,
if u find how i did it (lol) please let me be one the first to know pls,thnx