IIRC, you need to know the MAC addresses, so de-authorizing all then authorizing the remaining ones ( one Apple ID family, so its simple for everyone, and for syncing your purchases you kinda need to do it that way ) has been simpler and more convenient than rooting around for MAC addresses. Or something like that - De-authorizing all has been simpler.

Ed
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Fine! Ethel/Kate/Starmillway