a2billing - add 2nd outbound destination provider

Hello, I currently have an Asterisk - Freepbx - A2billing box configured for a call-forwarding application. My inbound origination - DID number provider is set, but I do not wish to use this same provider for all my traffic with the call-forwarding/outbound termination destinations under the A2billing header "Inbound DID: Destination", as i have found a new and "better" provider, i.e. cheaper. However, this new provider only covers 95% of my outbound termination destinations, so I need to keep the existing provider who also provides me my origination and DID numbers. So, I would like to add the new termination provider and be able to choose which provider to use when I configure a customer. You will need to walk me through adding this new provider for my outbound termination/call-forwarding destination. At this point, I do not feel it is necessary for you to have access to my setup, so we can do it via Skype. Thank you for looking and bidding.