Combining Oil heating with Boiler stove.

Maybe someone can help me with this, I've tried searching but nothing similar comes up.
I currently have a pretty standard oil fueled pressurised central heating system.

Would there be a way of incorporating a open vented circuit into the same radiators and closing off the oil boiler with ball valves, so I have the option of reinstating it in the future?

The system I have in mind is to add a feed and expansion tank in the loft, go straight up from the from the stove to the loft and then join the existing central heating circuit. Does anyone know if this is viable or can anyone offer any advice?