transit in beijing through Shanhgai (San Francisco->Shanghai->Beijing)

Hi,
I am flying to Beijing through Shanhgai (San Francisco->Shanghai->Beijing) with the same company (China Eastern). Considering point 2 in the conditions you explained above, can I apply for a 72h transit if I take a flight with a different company from Beijing within 72h of my arrival to Hong Kong for example?
Thanks in advance!
Regards,
Aritz