

Free transit at PEK based on separate reservations?
I purchased two separate tickets, a round-trip from San Francisco (day 1) to Beijing (day 7), another round-trip from Beijing (day 4) to Seoul (day 7). I plan to enter Beijing from San Francisco on day 1, and leave Beijing within ~68 hours heading to Seoul, on day 4. Then, I will come back to Beijing on day 7, and will take another flight to San Francisco within ~4 hours.
1. In my first entry to Beijing, can I take advantage of 72 hours transit by showing my ticket to Seoul (which is a different reservation from the one I took to arrive at PEK)?
2. In my second entry to Beijing, can I stay in the airport using the 24 hours free transit policy?
To sum up, is it possible to show the ticket to a 3rd country from a separate reservation?
(I am Korean citizen, so eligible for 72-hours policy.)