First - what is it you're trying to achieve - a slower wiper speed, or a longer interval in between wipes?
Second - a relay is essentially a switch, a switch that controls an electrical current, a switch that is controlled by an electrical current - to put it in simple terms, you use a relay when you need to control a large electrical current, using a small electrical current - what do you hope to accomplish by fitting another relay?
Last - Suzuki has been building & selling Altos since the early '90's - my Alto didn't even have an intermittent wipe function - what Alto do you have?
Ok, there might be a way around this. If yours only has the "off, int, on" switch then you might be able to wire in a separate variable wiper delay circuit.
Got a buddy that's good with electronics? basic astable 555 timer circuit driving a relay to run the wipers would be the way to go. Bypass the existing setup.