Foreign carriers who are permitted to operate to the US must submit a full and complete Master Crew List to the TSA/DHS in a specified format to maintain acreditation by the US. Once accepted and approved carriers must submit individual crewlists at least 24 hours in advance of arrival into the US (maybe arrival into US Airspace). The list is checked against the MCL. If there is a discrepancy the flight will not be accepted. FAA will not approve routing.
To my knowledge in the case of a Cargo aircraft. No other persons are permitted on the aircraft including charter representatives, ground staff, family and friends of crew. Depending on the nature of the cargo, it maybe necessary to carry a specialist cargo attendant. However, the TSA will need to be given time and probaly require alot of documentation and good reason as to why such a person is required to be onboard
before approval is given. In addition I believe carriers have to make crewlist submissions via APIS.
Things change so I may not be entirely correct but I am sure the US DOT / FAA / Customs and Immigration websites will give good guidance. Otherwise, my advice would be to invest in a good US
aviation lawyer.