Thanks for your answers, all help is greatly appreciated, so at the very least, I know I'm doing everything I can to help them find a way back. The description of Shadow; long haired, very fluffy and white, definitely fits the bill, I think. The torty and tabby definitions feel a bit difficult to get a precise understanding of. After looking at other peoples descriptions, it seems that Fifi probably is Like everyone says, tabby and white. It makes sense to omit the breed reference; they're both cross anyway, as it doesn't help.
Now I know what the desciption needs to be and just need to work out how I can change it, where possible, that is. Has to be time for another catnap first, thiough, that is after Hero(photo incl.) the one cat still with me, has been 'taken out'. That is, I daren't let him out on his own any more, not that he shows much inclination to be alone outside, so stay out with him.