Priorities in Mapping Sets-SLA

Hi All,

Can anyone plz clarify me on priorities of mapping sets in SLA. Let me breif abt my requirement.

1)There are charges that are getting calculated on a Sales Order at 15% on Return Orders with specific OM Types.When these return orders are interfacing to AR they should point to account-41100.I have created SLA,used Mapping sets to derive the 'Charge' name by using a custom source.If the Charge Name is 'Restocking Fee' then its going to 41100 Account segment with priority-01

2) If the Return Order is created with OM Type other than the above and having return reason as RMA/Warranty then i have a created a custom soruce to capture the return reason on AR trx lines and created Mapping set with priority as 02 in SLA