Hi.
How's this as an idea for a one off: one day, Simba's mother, Sarabi, happens to discover a very young Vitani while she is hunting in the Pridelands. Despite recognising her as an Outsider, and, that technically, she is trespassing, Sarabi, who knows full well how harsh life in the Outlands is, tries to persuade little Vitani to come back to Pride Rock and live with her as Sarabi's daughter.