Methods and apparatuses for processing orders in a computerized asset trading system when the order contains trading requirements for trading accounts that do not map to trading accounts recognized by the provider trading system. The invention books trading requirements associated with the unrecognized trading accounts against a default trading account set up for the customer by the provider, thereby allowing the order to be processed instead of rejected merely because one or more of the customer-specified trading accounts has not yet been approved by the provider. The invention also allows providers to specifically block customer trading accounts, and to dynamically create approved trading accounts as they are needed so that subsequent transactions involving the previously unapproved trading accounts will be executed without using the default trading account. The invention also rejects orders for customer trading accounts that have been specifically blocked by the provider.