Danke is German, Desi! Please watch out:
All you want to know the legal in and outs about a marriage in Indonesia, where one partner is foreign (in this case Dutch) you can find on http://www.netherlandsembassy.(...)id/html/huwelijk.cfm
(also a Bahasa Indonesia version)
The Netherlands marriage laws allow only monogamic marriages, and those can be male/female, male/male and female/female (the last two recently). That doesn't mean that you can't have a polygamic marriage, only that one (in general the first) marriage is legally aknowledged, and that you cannot marriage another person in the Netherlands unless the existing marriage is annulled by divorce. Children born out of relationships outside the existing marriage cannot be legalised by the natural father (if he is married to another woman)! If a married man or woman marry somebody else in another country there is nobody to stop you. It will only be impossible to legalize that marriage in the Netherlands. If you want to marry in the Netherlands and you are a foreigner you are obliged to show a document that states that you are not married. The funny thing is that some countries (even in Europe) don't issue this kind of documents. If this is the case it depends on bilateral treaties if the Netherlands accept this.
Concerning your last question; a child born out of a mixed marriage or relationship in Indonesia where a Dutchmen is the father. If the marriage is officialy registred in the Netherlands then the child will get automatically the Dutch nationality (providing the birth has been registerd at a Dutch consulate or the embassy. In the case that the marriage is not registred or in the case of a different partnership, the child wil only receive the Dutch nationality 5 years after it has been legally aknowledged by the father at a Dutch civic registry (new rule effective from april 2003).
Pffff, need to know more?