RVDT: If I had the data I needed to do a proper weight and balance with the aux tanks in the EC135P2e/T2e (internal aux tank), EC135P3/T3 (external aux tank), EC145 and EC145T2 I would. I don't have all the data, only some of the basic weights to get a full fuel (main and aux) payload.
Perhaps you can share more info so I can do a proper weight and balance.