Shekou to HKIA

Hi, i bought a round trip ticket (SIN to HKG, HKG to SIN) from Cathay Pacific. I plan to start off in HKG, before heading to GZ and ending the trip at SZ. Can i confirm that I will be able to depart Shenzhen via Shekou and take the ferry to HKIA on the day of my flight back to SIN?

Thanks much!