Ok to have layover in mainland China on return trip home after using 144-hr exemption?

Hello,
Someone answered this elsewhere but I can't find the answer!
We are flying Seattle>PVG (staying less than 144 hours)>HKG.
Our return trip is HKG>PEK (5 hour layover)>Seattle.
Am I correct that we can use a 144-hour Visa exemption for our time in Shanghai? Is it a problem that we have a layover in Beijing on our return trip? Or are these treated as two separate entries? We are hoping to use the 144-hour exemption for our time in Shanghai and then use the 24-hour TWOV (or direct transit?) since we will not be leaving the Beijing airport. Will that work? We just want to be sure we don't mess this up!

Thank you very much.