I think unlikely system 4 aircon have 8.5A power capacity. A non inverter system 3 is already on 7.6A. Why not u get 2 aircon systems, one system 3 for the room and one single unit for the living room? Of cos you are restricted to turn on 2 aircon system at the same time. You cant choose a smaller BTU aircon unit to cool 3 bedrooms and a living room as it don't work this way. For example: a system 3 aircon unit is sized and match accordingly to the 3 bedroom space and it usually reaches it's full BTU capacity. There is no way to put in a blower unit in a living room. Just my 5 cents thought. Hope its useful to you.. PIG.