At the risk of being repetitive, I just wanted to ask if all of the people on the charter
boat that are sailing from the BVI to the USVI and back are U.S. citizens or LPRs? If not, be aware that they will need a visa in their passport in order to enter via sailboat - the ESTA visa waiver doesn't apply.
A very easy workaround is to have any non-Americans take the ferry
from the BVI to the USVI, or if they are flying to the BVI via the USA they will have a stamp in their passport with a remain-until date past the sailing trip to the USVI and thus are already legally "in" the USA for that duration.
I'm anchored in the northern coves of St. John at the moment and it is wonderful here!
The clearance papers from the BVI to the USVI will contain all the people aboard the vessel when leaving. When returning to the BVI from the USVI you don't need to clear out and the BVI is used to boats arriving with no exit papers from the USA; so the entry documents will reflect the number and names of the people actually aboard when returning from the USVI.
Just remember to pay the park fees
and to ensure that your holding tanks
are closed and that you empty them only when more than 3 miles offshore
(or use a pumpout in the USVI, they don't exist in the BVI).
Unless you have a shallow draft
boat, in which case you can anchor
inside while clearing in, you should take a mooring
ball just around the corner at Caneel Bay and then dinghy
in - don't tie up at the customs dock
but at the dinghy dock
to the far left as you enter the bay and walk to the Customs
& Immigration building.