Hi,
Getting FMUP127 is not linked to your FMDERIVE rules (at least, not directly). This error is issued by SAP in order to avoid data inconsistency when FM account is changed in a chain of documents. You have to read carefully note 2090247 - FMUP127: how to analyze, debug and the main notes. which will give you the perspective on how to deal with this situation.
Regards,
Eli