As far as I can remember the normal case is actually that the children share 50% of the estate among themselves and the spouse gets the other 50%.
Now with regards to the "Pflichtteil" (or the compulsory amount that has to be given to heirs), it is as follows:
- 75% of the 50% share of the children (=37.5%) and
- 50% of the 50% share of the spouse (=25%)
The remaining amount (37.5%) is then free to be given away at the discretion of the deceased. Hmmm.. sounds complicated!!! Note that should this said "Pflichtteil" be violated, for example so that the surviving spouse could continue living in the matrimonial house ("Nutzniessung"), this should be executed through a (prior) testimony.
Note that the given information above is from someone without expertise with the Swiss law & based solely on some lectures attended in Swiss ZGB. It would be at your best interest to consult a lawyer.