We also have 3 different types as you have mentioned and all of them have different sequence numbers. The system did it on its own when we started 8 years ago.
There are two different banks for currency USD and CAD. Each bank account has multiple payments methods for Electronic payments. Each electronic payment method has its own sequence. Recently I had created a new electronic payment method for our USD account and Epicor assigned a new sequence to it on its own.
Thanks for your comments. Do you know if it is possible to customize the sequence number? I would like to have the first sequence starting with 3, the second one with 5 and the last one by 9.