A recently proposed document format: Publicly Posted Composite Documents (PPCDs) [1] has been developed to tackle both the containment and security aspects of composite documents participating in inter-organizational workflows. Here, the access control and authentication material together with the actual contents form a tamper proof digital bundle that was designed to be securely transmitted over potentially low security channels. Though PPCDs can be created, shared cross-organizationally and edited using software on a computer, a key functionality to efficiently and securely incorporate scanned documents inside Multi-Function Printers (MFPs) was missing. We solve this problem by enabling users with assigned modification rights to specific content-parts of a PPCD, to update such parts through scanning physical documents at a standalone MFP. The scans are then securely and automatically encrypted, signed and inserted as new PPCD content. Thus, in this paper we provide a comprehensive solution for document workflow participants to securely update or insert new contents to the PPCD at a standalone MFP device through non-trivial extension of HP MFP firmware.