I am flying from Frankfurt to HKIA via Emirates on May 24th.

Yes, of course. You can take the ferry at the Skypier to ZH directly. The ferry will depart at 12:15, 14:15, 17:00 and 20:10 on May 2nd. The ticket fare of an economy class is CNY210/person. If you go back to Frankfurt from HKIA directly without going out of the airport on May 28th, then you can take the ferry back to Skypier on that day. This ferry will depart at 09:30, 12:40, 15:25 and 18:35 on May 5th. The price of an economy class is CNY290/person, while the first class cost CNY370/person. You can book the ferry tickets on the official website of Chu Kong Shipping Enterprises (Group) Company.

Thank you Sally.
I gusse you meant taking the ferry on May 24th to ZhuHai and then back to HKIA via Ferry on May 28th.

Thanks,
Lisa

Yes, you are right.