At the outset, it should be mentioned that there are many unheard of narrations circulating through the blessings of ash-Shaykh Email, al-Allāmah Blackberry and al-Mufti Facebook etc. The scholars are under no obligation to verify each of these circulations. The onus is upon the circulator to prove the authenticity of what he distributes.
عن ابن عباس رضي الله عنهما أن رسول الله صلى الله عليه وسلم قال… البينة على المدعي
Rasūlullāh صلى الله عليه وسلم said, “The burden of proof rests upon he who makes the claim.” [al-Bayhaqī]
That being said, my instinct tells me that the Layyā “narration” is but an attempt to provide a female equivalent to the Ḥadīth mentioning Yūsuf عليه السلام as being Nabī, son of Nabī, son of Nabī, son of Nabī.