Apr 10, 2015 - 10:12 AM
Welcome to MySwissAlps! I suppose you are referring to the 3-day Swiss Travel Pass Flex Combi, right? For the children, you will receive a free Swiss Family Card so they will travel along for free everywhere you go (within Switzerland).
Just buying point to point tickets will be too expensive as I assume you will be traveling by cable cars/cogwheel trains during your stay. You need a rail pass to get a discount on those. Whether the Swiss Travel Pass Flex is the best option depends on your exact travel plans; day trips included. For most people, a Swiss Travel Pass (so not the Flex variant) or a Swiss Half Fare Card works best. But there are passes for just the region as well. They're all explained on our website.
A Swiss Travel Pass or Swiss Travel Pass Flex includes a free train ride to Basel, at the border. So you don't need a ticket for that leg. You only need one for Basel to Paris. Details can be found here. I am not sure which website you meant when you wrote "when I tried to buy through this website". We don't sell tickets, but the websites listed here do.
As you live in Thailand you can get your pass and ticket from the same local website: