that is a bummer, but perhaps there's a solution below.

I think you fly to TPE often from North America, one potential suggestion I have is buy I/D fare and start your tickets ex-TPE. Then, constantly keep one ticket open. Aka, you are in the US working and with your family, while in the middle of a trip.

For example: (I think you're based in the US):

*USA-TPE: Burn miles to get there first time or buy cheap one way, etc.
*Buy ex-TPE-HKG-JFK /[long stay in US, until your next "trip"]/ -HKG-TPE.
*Each time you're in TPE, you'll be ending/starting a new ticket. So you could then do your China side trips that way TPE nonstop to China destintinations, which it sounds like you also do frequently.
*The downside is ex-TPE I/D fares do not allow HKG stopovers, but provided your business priorities are China and Taiwan that should be okay. Btw, a "transit" is 24 hours so you could easily do a day of meetings or dim sum in HKG without breaking the stopover rule.
*The huge upside here is you probably won't be paying too much more (ex-TPE I/D fares aren't that much more expensive than the higher priced W/R fares), and you will most certainly be back in the running for DM status again, since I and D earn like today's rates.

The one thing I'm not sure of is the stay conditions in North America on I and D fares ex-TPE. You'll obviously need them to be at least 3 months for this to be a reasonable possibility.