We’ve been informed you that for Multiple entry to entering to China , The embassy is required the Official Invitation letter with sealed code from the Chinese Government or Government-authorized Chinese companies. And your citizens cannot apply for express case. Just Normal case 4 working days only. If this document is not available the embassy staff cannot allowed to you apply multiple type visa for sure (as we’re experience) but we will try to be apply to you again.
Could you please explain about 2nd passport (as I’m understood, you handle 2nd passports and have Thai re-entry both right?