A-Level Maths: must include C1, C2, C3, C4 and one of the following combinations: M1 S1, M1 M2, S1 S2, D1 S1, D1 D2, D1 M1. To get an A* you need 480/600 overall including at least 180/200 from C3 and C4.
A-Level Further Maths: must include FP1, the best result out of FP2 and FP3, and four other modules not already used in regular maths A-level. To get an A* you need 480/600 overall, and at least 270/300 from the best three A2 modules.
AS-Level Additional Further Maths: The three remaning modules. To get an A you need 240/300 overall.
So, in the example you gave, you would have C1-C2-C3-C4-S1-S2 (say) in Maths, FP1-FP2-FP3-M1-M2-D1 in Further Maths (the only A2 modules here are FP2, FP3, M2 so they need to average 90% for A*) and then D2-S3-M3 in Additional Further Maths.
All this information is in the specification on the OCR website, it does get quite confusing though when you have a lot of modules!