Conditional display of Lines in SOH4 Screen

Hello all,

I'm new to Sage development so please bear with me. I'm on Sage x3 v11. On the Sales Orders, I want to exclude certain line items from displaying on the sales order grid. Before this effort, the user has to manually remove the line item before continue processing. 

I have found the screen (SOH4) that has the line items associated to the sales order function (GESSOH) and the specific script (SPESOH). I can't seem to find any specific information on how or if i can do this (exclude certain line items) but I believe this will be done in the specific script. 

Do I need to add an action to the screen (On Initialization for example) before adding my code to the action (AFFMASK  i think in this case) in the SPE script? I feel like i'm missing something. Any guidance would be appreciated.