MANOVA: Dependence in dependent variables In my study, I have two age groups (YA and OA) and 3 scores (A, B, C) are collected from each participant. Here I'm interested in two dependent variables, "RCG" which is calculated by subtracting B from A and "DSC" which is calculated by subtracting C from A. I'm planning to run an MANOVA test with age group as the independent variable and RCG and DSC as two dependent variables. I'm expecting to find an interaction such that there is a group difference in DSC but not in RCG.
As both RCG and DSC are calculated from score A, I assume they are not completely independent from each other. Would this be a violation of the MANOVA assumptions? The correlation between RCG and DSC is about 0.5.
Is there another statistical method that is more appropriate to use here?

MANOVA is a multivariate analysis method created just to be able to model dependence between outcome/response/dependent variables, so you are certainly not violating assumption for that reason.
