@daducci I would be more clear here, as it is not clear why you need both (i) volume fractions from MrTrix and (ii) directions from ball&stick (that indeed can provide you also with volume fractions). Also, MrTrix can give you the directions if you want (and probably much faster). You need to justify why you are using (and mixing) so many models (DTI for the FA, MrTrix for the 5 volume fraction, ball&stick for the directions, then SH to generate the FODs (that you can actually get from CSD)…). It is a bit too complicated..