1605@ 18h15 , arriv from Germany > Hangzhou, China + flyback 18/05 @ 19h Hangzhou-via Hongkong(2h)

Is there any chance that we can use this 72h or 144 h visa for a short stay in Hangzhou from 16th -evening- til 18th evening ; the flight is arring from Germany - via London + short change of fligths in Hongkong ( 13h40 arriv on 16th May, continue from Hongkong 16h - arrive Hangzhou 18h15 ; same with the flight back:on 18th MAy leaving Hangzhou- via Hongkong 8 arriv 21h35, ff. 23h45 to London ff to Haj (Hannover Germany ) - can Hongkong be counted as third country stay ? - how long should he stay /stop over in Hongkong to be accepted as "third country" on way back - 24h ?
Thanks your kind reply Heidi