Hey
Lucille,
on the main page you can add information for a name if you go through the 'submit a name' and then go to 'correct an existing name', you could also e-mail
Mike if you have a long list. Also adding them to the 'comments' section would be useful, since that's where people tend to look for pronunciations if it isn't with the name.
about the pronunications:
I'd say that the pronunciations for
Heike /
Heiko are pretty much the same as the
German ones, the EI (or IJ for that matter) would be like something in between IE and EY, so HIE-ku would be valid as well (same thing for
Eilert, I'd write that as IE-lurt). And for
Dieuwke, I would say it's pronounced more like: DEEOOW-ku / DEEW-ku, because with DEW-ku, you can't hear the 'i' that is in there.
Also
Japik would be YAH-pik (because otherwise you'd get something like djapik (Dutch pron.) if you know what I mean).