Sample if I have a ticket SEA-PEK-SEA on March 1 and return March 30.

But have separate ticket from PEK-HKG_MNL-PEK

I have the following itinerary. Can you please tell if this will work for the 72-hour free transit?
SEA-PEK = March 1
PEK-HKG = March 3 (on separate ticket) stay Beijing for 2 days
HKG-MNL = March 6 (on separate ticket)
MNL-PEK = March 28 (on separate ticket) stay in Beijing 2 days OR not can go straight
PEK-SEA = March 30

thank you.