Cedrella Black (disowned, dates unknown)
Daughter of Arcturus and Lysandra Black.
Two sisters: Callidora and Charis (BFT).
Married to Septimus Weasley.
Disowned because she 'married Septimus Weasley' and represented by a burn hole in the Black Family Tree (key#4) (BFT).

Отсюда же:
Dorea (Black) Potter (1920-1977)
Daughter of Cygnus and Violetta (Bulstrode) Black (BFT).
Three older siblings: two brothers Pollux (1912-1990) and Marius (disowned, dates unknown), one sister Cassiopeia (1915-1992) (BFT).
Married to Charlus Potter; they had one unnamed son (BFT).
It is doubtful that Dorea is Harry's grandmother because Jo has told us that "James's parents were elderly, were getting on a little when he was born, which explains the only child, very pampered, had-him-late-in-life-so-he's-an-extra-treasure, as often happens, I think. They were old in wizarding terms, and they died." (TLC) Dorea was only 57 when she died.
Possible name derivation: related to the names Dora and Dolores; Dorea is a bacterium found in human feces. Not a star or constellation.