"I told you, I followed a lion-"
"Followed a lion?" Shenzi asked, sitting down, looking very unimpressed with the young lioness. "In here?"
"Yes." Zira snapped. "I told you he-"
"Such a liar. What should we do with her Shenzi?" Banzai asked, grinning wide.
---

I don't think Scar told anyone about his alliance with the hyenas. Zira, obsessed as ever, followed him one day and found herself face to face with the main trio. Also, she's not full grown here. I don't think she's as old as Scar, but older than Simba.