The ERPI metadata rules show the target application dimensions on the left (Account, Entity, Etc) and the EBS segments on the right.
So if you want to create a metadata rule to combine 2 EBS segments into 1 Target EPM application dimension, you must use the Concate type. You cannot use the FDM method (in metadata) when trying to combine segments.
I apologize but the request you have is far too detailed for an answer in a forum. Your project requirements would need to be more fully reviewed. This is not something that can be accomplished in a forum.
I would suggest spending some time reviewing the ERPI admin guide. If you still require assistance, you may want to consider engaging a qualified consulting partner.