Could it perhaps be the case that the relationship between Sah and Sopdet and Sopdu was expressed in the form of a triangle, and that this is the basis of the associated hieroglyphic in the names of Sopdet and Sopdu, and also does the Sopdet/Sopdu triangle have any connection to the triangular/cone shaped bread offerings...?
"Look, Osiris is come as Sah: the Lord wine-colored with supplies, the perfect one of whom his mother has spoken, the heir of whom his father has spoken, the one whom the sky has conceived and the morning-star has given birth." The sky shall conceive you with Sah , the morning-star shall give you birth with Sah . Live! Live, as the gods have commanded you live. With Sah in the eastern arm of the sky shall you go up, with Sah in the western arm of the sky shall you go down. Sopdet, whose places are clean, is the third of you two: she is the one who will lead you two in the Marsh of Reeds to the perfect paths of the sky.
P 38 (N 9); PT 442 ยง819
Re has taken me to himself,
To the sky, to the eastern side of the sky
As this Horus, as the dweller in the netherworld,
As this star which illuminates the sky
My sister is Sepdet,
Never again will the sky be void of me,
Never again will the earth be void of me
Bring this to me and I will be your third in On
Utterance 266, lines 361-363
Utterance 504, lines 1082-1083
Pyramids of Kings Pepi I, MerenRe and Pepi II
The sky is pregnant of wine,
Nut has given birth to her daughter the dawn light,
And I raise myself indeed
My third is Sothis, pure of seats
As Sah and Sopdu are generally thought to be representative of singular stars, it seems likely, though none is ever suggested, that the same would be the case for Sopdu, therefore could the triangular motif be indicative of the relationship between these three stars/
Morph