Hello Gareth,
Apologies for the late reply. It was a rather complex process but in my 6 weeks in Taiwan I managed to obtain the required documents to marry and register with my wifes household which enabled me to obtain a British passport for my newborn baby. Must have been almost 50pages posted out to HMPO (inc a colour copy of every blank page in her new Taiwan passport as well as mine) but her UK passport was issued less than one month after which was fantastic!
It was a ‘letter of single status’ that was issued to my mums home from the local registry office. She forwarded that to the Taipei representative office in the UK to be certified. Once returned to my mum she posted that to the ministry of foreign affairs in Taiwan to be certified again. This was returned to my wifes Taiwan address for us to collect when we arrived. We then took this to the local courts to be notarized and finally to the local registry in Taiwan for us to be officially wed. In the end I didn’t have to fly anywhere that I wasn’t going anyway but we must have made the hour commute to Taichung at least 5x to obtain the relevant docs for our daughters UK passport.
Hope this helps…