Is it possible to implement a Global Label Management printing solution which is triggered by a GR or PO and processes/prints the labels in the background rather than the GLM Manual print transaction?
GLM is a user interactice print process and provides no API for automatic printing. If you like to implement automatic printing then you have to build your own API. To do so you can use the subroutine L_PRINT_START of the function group CBGL_MP10 as a sample or starting point. All data which is coming from the screen have to be provided from your program then.
An alternative could be a solution from the SAP Services Sustainability Hub - Global Special Expertise Team. They offer a customer solution based on a framework which allows you to implement automatic print processes for GLM much simpler than doing everthing by your own.