Order Management -modifying orders not through STNE or MOM

[Backwoods]

Does anyone know of a plug-in for shop-site that can manage just order management. I am looking for something that can handle adjustments to orders, process returns, exchanges etc within shop-site. I am currently using MOM but needing to move the fulfillment piece to our warehouses own fulfillment software that does not support any monetary features/ order processing.

The fulfillment system will only handle check-in of inventory, pick, pack, and ship. It also can send an RMA to the order manager to process a return to the customer if received.

Thanks!

Matt