They beat Leander Paes (India) and Andre Sa (Brazil) 6-3 7-6 (4) in an entertaining quarterfinal match on centre court on Thursday night.
With Artem Sitak and American Nicholas Monroe also progressing to the last four earlier on Thursday, there is the possibility of two Kiwis featuring in the ASB Classic doubles final.
Paes and Sa are a highly experienced combination - with numerous titles to their credit - but Daniell and Demoliner showed more composure in the crucial moments.
They took their only break point opportunity to seal the first set, then stayed strong as Paes and Sa threatened a comeback in the second set.
The Kiwi-Brazilian duo always looked more likely in the second set tiebreak, and Daniell sealed the match with a strong serve and well placed volley.
