Trying desperate to make this work, I want a remade version of Sunset Valley to fit all expansions. Now its become somewhat of an obsession...

I have made a, in my own humble opinion, pretty good job with this and has come as far as a weddingparty at the shore, but when I wanted to take them to France for their honeymoon, they dissappeared?

I'm almost positive that it's somewhere in the building process, because I can travel from Riverview, Sunset Valley and so on.

I'm equal positive that I forgot to erase the two files WPID 0xF609FD60 and UNKN 0x296A6258, could that be the reason and if so, how do I erase them now, with a fully built world (Empty lots, but everything is done)

Hoping for some thoughts?

There are nobody with any experiences they want to share? Am I the only one that have had this problem?

carisod, sims vanishing when travelling is a known game bug, try Twallan's traveler mod to prevent this from happening.
http://nraas.wikispaces.com/Traveler

It shouldn't be to do with those files that you mentioned, as long as you are using your version of Sunset Valley as an overide.