Right now this IFC does not exist with Opera or G&L, maybe you can go to P.S.
What I believe that can be possible to develop is that Simphony or RES store the information in same database after the Room Charge is done or after the customer is identified in the POS, the identification must be to Opera.
Then when the customer is identified again in a new transaction, the POS should go this Database and check the history and suggest the last order or the most requested product (s).
Of course this is a P.S interface.
With RES you can do this with GSS (order history), but of course the customer is not the one in OPERA, because are 2 different customers databases and does not exist any sync process between Opera and RES GSS database.