RaskolnikovsGarret
It's a review of marking, not a remark so as long as the person reviewing thinks the mark scheme has been applied fairly and accurately then there's no changes. If it's out by a band then there'll be changes. Marks can go down as well as up.
I always say that because it's different to the remarks of old. I think boards got fed up of schools who were, rightly, sending for remarks on significant numbers of scripts and then having loads go updue to poor marking.
Personally I wouldn't go for a review when she's that close to the 6 boundary because I think it's a much bigger gamble than being close to the 8. However, if one paper is substantially lower than the other and it looks like that paper may have the 6marks then talk to the teacher about whether they feel it would be a good decision as it would be in some cases.
Your DD friend who got a 5 I would go for a review.
I know loads of English teachers this year who have said their more able grades are out of line this year and they don't know why, well, they do as most of us know people who've examined and it was a shit show this year.