Swiss rail cards...which is best?

[CATTY15]

Hi,
We are planning a short trip to Switzerland in the summer holidays with 3 kids, all under 16.
We want to go on the jungfraujoch train to the mountain top.
I've just looked at prices and it's very expensive .
There seems to be lots of different rail cards available which will give various different discounts but I'm a bit confused as to which is our best option.
We are not planning any other mountain trips I don't think but are open to suggestions!
Has anyone done this recently and have any advice please?
Thanks

What are your plans?

We're going to Saas-Fee in August by train. We've got a 3 days in 1 week Swiss Travel Pass Flex which is for non-consecutive days as we won't want to leave Saas-Fee during our holiday.

Hi,
We're staying at Interlaken, the main reason is to go up jungfrau

Excursion trains like that are covered.

You need to work out how many days in total you'll travel by train and whether they'll be consecutive or not. Include any airport transfers in that.