This should do the work @Pinny
Leave the two graph extensions in your extension so your code overrides the Workflow and Approval engine UI manipulations and of course, you need to modify the code based on the extension and udf fields you have added.
using PX.Data;
using PX.Objects.PO;
namespace HCL
{
public class HCLPOOrderEntryWF : PXGraphExtension<POOrderEntry_ApprovalWorkflow, POOrderEntry_Workflow, POOrderEntry>
{
public static bool IsActive() => true;
protected virtual void _(Events.RowSelected<POOrder> e)
{
if (e.Row == null) return;
PXUIFieldAttribute.SetEnabled<HCLPOOrderWF.usrHCLApprovalRouteID>(e.Cache, e.Row, true);
e.Cache.AllowUpdate = true; // you may need this line to be able to save but first try without this line
}
}
}