Rare should consider turning the Merchant Alliance into a delivery system, ala Uber Eats. You place your "order" for supplies (wood, food, cannonballs, supplies crates, etc), then fire a special signal flare. The nearest merchant alliance emissary spots it and takes down your order, and distributes it across the alliance.
Now other players can choose a Merchant quest that has the players stocking up on your requested supplies, then delivering them to you. It should cost a lot, to make it worth it for the Merchant, and be expensive for players. But for PLs with millions who don't care about gold, it would be a convenient place to sink some coin.
How do you prevent one crew from abusing the other? Uber has already figured this out. The merchants keep a ledger with a rating system, and both crews rate how the transaction went. Pirates who use the system for grief will be poorly rated, and won't be selected for future trades.
