@Solla-topee 

No, the linked instructions are of no help whatsoever to the problem noted; I had already performed "Add to Apple via Matter".

This allowed the simple task of operating (i.e., turning on and off), but not family sharing (which is why I bothered attempting

with Tapo app to begin with). Once I started with an unconfigured plug and configured via Tapo app, I found a firmware update

was required (though no mention of such a need with iOS Home app, nor any FW update schedule).

Both apps assume I'm starting from an unconfigured state (i.e., from scratch), rather than simply attempting to augment an

existing configuration done via the other app. And I only add one of the four supported Matter platforms...