I know some people who have both names. For some situations (and some documents) they use their husbands name; but on others (like their passport) they have a different name. In fact, this one person I know, I had no idea her "official", i.e. passport name, was different from the name I have known for by for years and which is on her ID card, job title, email, etc etc.
So it may be possible to just leave the Germans to their own devices, changes everything else here in HK and just live with it.
GovHK: Frequently Asked Questions – Hong Kong Identity Card
Q21. What documents should be produced for amendment of name, date of birth or place of birth on my identity card?
If you want to change your name, you should produce documents relating to your change of name such as deed poll, marriage certificate or travel document.