Addtional A/C vents

[Sleepcare]

Our Ertiga is GA(entry level) with front A/C vents only.
Ask ko lang approximately magkano kung padagdagan ko ng vents to cover the 2nd and 3rd rows? Configuration is implant sya hindi yung naka expose na naka-screw lang. Need ba palitan yung A/C system mismo i.e, compressor etc., ?

TIA

Balak mo ata boss yung katulad sa revo/crosswind/adventure na rear a/c configuration.

Ask nalang yung mga nakapagawa na before.