Alright so I was looking at some theories on the source here and thought of one that some might also think.
What if Sarabi and Zira were sisters? Why? Well... their fur is almost the same color and during an early concept of the first TLK, Sarabi was pictured with a stripe on her head similiar to Zira's.
Don't know what you think but this is one of my theories.
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Characters(c)Disney
Base(c)-Tytos-
However, I /do/ see her as Sarabi's daughter with Scar.