The OpenSound Navigator is the heart of the OPN, so it is now pretty official that the Phillips Hearlink is not really the OPN. It is most likely the Sonic Enchant product then. I don’t really know much about Bernafon but there’s a possibility that Bernafon and Sonic share the underlying technologies as well.
It’s entirely understandable that the OpenSound Optimizer (the feedback prevention technology) can be separated out and used independently from the OpenSound Navigator technology. So I’m not surprised that William Demant implements this technology on the Phillips Hearlink.
Similar with the Lithium Ion rechargeable technology, it can easily be adapted by any of these sister brands. Having the same rechargeable technology on the OPN S and now on the Phillips Hearlink doesn’t mean that the Hearlink is the same as the OPN S.