Hyphenated goddesses

[ikhet_sekhmet]

I'm very curious about the identification of the Eye of Re with the Eye of Horus, and what this has to do with the identification of goddesses like Bastet and Wadjet. First stop: the Lexikon der ägyptischen Götter und Götterbezeichnungen, a huge dictionary listing every deity name and giving their attestations. In German. It's very educational, especially when there are words like "Kopfschmuck" to be learned.

Anywho, the Lexikon lists numerous instances of Bastet being conflated with another goddess:

Bastet-Wadjet
Bastet-Wadjet-Shesmetet
Bastet-Unut
Bastet-Werethekau
Bastet-Menhit-Nebetuu
Bastet-Sekhmet
Bastet-Shesmetet
Bastet-Tefnut
ETA: Bastet-Sothis

And, amongst various titles:

Bastet, Eye of Horus

Not to mention:

Wadjet-Menhit
Wadjet-Sekhmet-Bastet
Menhit-Wadjet
Menhit-Bastet
Menhit-Sothis
Menhit-Sekhmet
Menhit-Sekhmet-Bastet
Menhit-Sekhmet-Bastet-Wadjet
Menhit-Tefnut
Mut-Wadjet
Mut-Wadjet-Werethekau
Mut-Wadjet-Sekhmet-Bastet
Sekhmet-Isis
Sekhmet-Bastet
Sekhmet-Bastet-Werethekau
Sekhmet-Bastet-Raet [aka Sekhmet-Bast-Ra, aka Mut - Book of the Dead Ch. 164]
Sekhmet-Bastet-Tefnut
Sekhmet-Mut
Sekhmet-Menhit
Sekhmet-Neith
Sekhmet-Nut
Sekhmet-Hathor
Sekhmet-Tefnut

And my favourite:

Mut-Wadjet-Bastet-Shesmetet-Menhit

ETA: Sekhmet-Wadjet appears in Chapter 23 of the Book of the Dead.

That gives me plenty to go on. But something I'm not clear on is how Egyptologists know to use a hyphen - that is, when the name is a conflation of the goddesses and when it isn't. Why is Mwt-Tm "the mother of Atum" and not "Mut-Atum"? Mostly the conflations are just long strings of names, but in some cases, such as Bastet-Sekhmet and Menhit-Neith, they're unmistakenly a single word, with all the determinatives coming together at the end instead of ending each individual name. And does the order of the names carry any meaning?

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Leitz, Christian. Lexikon der ägyptischen Götter und Götterbezeichnungen. Dudley, MA, Peeters, 2002-2003.