If you do a bit of investigation, you'll notice a couple things.
First, Orders is the grid data view.

Browsing the source code for that screen, you'll notice that that data view has a data view delegate called orders with the line below:
public virtual IEnumerable orders()
{
// ... //
PXSelectBase<SOOrder> cmd = GetSelectCommand(filter);
// ... //
}
The method GetSelectCommand(filter) is defined like this:
protected virtual PXSelectBase<SOOrder> GetSelectCommand(SOOrderFilter filter)
{
PXSelectBase<SOOrder> cmd;
switch (filter.Action)
{
// ... //
case WellKnownActions.SOOrderScreen.PrepareInvoice:
cmd = BuildCommandPrepareInvoice();
break;
// ... //
}
return cmd;
}
The method BuildCommandPrepareInvoice() is defined like this, which further filters the orders returned:
protected virtual PXSelectBase<SOOrder> BuildCommandPrepareInvoice()
{
var cmd =
new PXSelectJoinGroupBy<SOOrder,
InnerJoin<SOOrderType, On<SOOrderType.orderType, Equal<SOOrder.orderType>, And<SOOrderType.aRDocType, NotEqual<ARDocType.noUpdate>>>,
LeftJoin<Carrier, On<SOOrder.shipVia, Equal<Carrier.carrierID>>,
LeftJoin<SOOrderShipment, On<SOOrderShipment.orderType, Equal<SOOrder.orderType>, And<SOOrderShipment.orderNbr, Equal<SOOrder.orderNbr>>>,
LeftJoinSingleTable<ARInvoice, On<ARInvoice.docType, Equal<SOOrderShipment.invoiceType>, And<ARInvoice.refNbr, Equal<SOOrderShipment.invoiceNbr>>>,
LeftJoinSingleTable<Customer, On<SOOrder.customerID, Equal<Customer.bAccountID>>>>>>>,
Where<SOOrder.hold, Equal<boolFalse>, And<SOOrder.cancelled, Equal<boolFalse>,
And<Where<Customer.bAccountID, IsNull, Or<Match<Customer, Current<AccessInfo.userName>>>>>>>,
Aggregate<
GroupBy<SOOrder.orderType,
GroupBy<SOOrder.orderNbr,
GroupBy<SOOrder.approved>>>>>(this);
if (PXAccess.FeatureInstalled<FeaturesSet.inventory>())
{
cmd.WhereAnd<
Where<Sub<Sub<Sub<SOOrder.shipmentCntr,
SOOrder.openShipmentCntr>,
SOOrder.billedCntr>,
SOOrder.releasedCntr>, Greater<short0>,
Or2<Where<SOOrder.orderQty, Equal<decimal0>,
And<SOOrder.curyUnbilledMiscTot, Greater<decimal0>>>,
Or<Where<SOOrderType.requireShipping, Equal<boolFalse>, And<ARInvoice.refNbr, IsNull>>>>>>();
}
else
{
cmd.WhereAnd<
Where<SOOrder.curyUnbilledMiscTot, Greater<decimal0>, And<SOOrderShipment.shipmentNbr, IsNull,
Or<Where<SOOrderType.requireShipping, Equal<boolFalse>, And<ARInvoice.refNbr, IsNull>>>>>>();
}
return cmd;
}
I believe you could override this method with one that defines what you're looking for, specifically the last section.
I realize this is not a working answer; however, I hope it is helpful.