Your parentheses seem to imply that the OpenBSD team only started PF, and then let go of development, which isn't the case at all. The OpenBSD team is still the lead developer of PF, and FreeBSD sources changes from "The Source". To the best of my knowledge, there are no notable PF forks around from which the OpenBSD team can, or ever have sourced changes from, but I'd be happy to learn otherwise if you have any accounts to share.
Because the developers of pfSense are FreeBSD users? I fail to see your point with that. And I beg to differ regarding the "no lead developer". Indulge yourself by looking at the OpenBSD changelog from release to release, year by year, and notice how every single change, minor and major, stems from there, and radiates out to, f.e., the PF port in FreeBSD.
