Hiya!
You can make overnight oats however you like. If you're using the oats as a HEB though you should be using 40g, not 30g. I make mine with strawberry Muller Lights all the time, though I only use one yogurt as I like the mixture to be quite thick but 2 would be fine too. I never layer them either like the SW website says as I can't stomach dry oats and there's a chance that if you layer them some of them won't absorb any yogurt. I just mix them completely with the yogurt, leave overnight and chuck a load of fruit on it in the morning. It's very nice!