The rules section does not specify how and in which order multi-ship melees are resolved. I'll post a note here for comments and edit, so that it can eventually be added. But I ran into an immediate question that I don't know the answer to. In the scenario with three opposing sides, if, say, a French ship and an English ship both send OBPs attacking a Spanish ship, which either has a DPB or none at all, how is that resolved?