I once was looking for a blood relative back in the ‘old country’ in Europe and contacted the local visitor bureau in the small town where they, I believed to be, were living. Told them my story with obviously my same last name (corresponding to my email address) and they politely replied with a few names, but only addresses and phone numbers.
Now, you/your dad have 2 options:
- easier way: find and pay an investigator in Taiwan and give them all information you have.
- harder way. Start googling everything. Old company name (maybe old colleagues have FB or something that mentioned that company. E-mail police stations near that old company. There have been stories of police helping people find lost friends/relatives. Better results if you do this in Taiwan, so the police see you are being truthful. There are all kinds of ideas to suggest, but most are so simple that they don’t need to be put down on paper. Make it a family project.
As with amything, the more public information you give of yourself to police or government bureaus through emails, etc. the more likely they may help (and not think you are a stalker). And that means everything. Like simple question: what was this Taiwanese woman to your father? Hopefully more than just something “online”.