You can't 'replace' Left Eye. I find that so disrespectful when people use that word. She was the biggest character in the group and one of the main reasons TLC were successful was because they all stood out in very different ways. Its not like the Supremes or En Vogue or even DC, TLC were about each character and what they bought to the group which is why they worked so well but it also meant that they wouldn't work well as solo artists. The T, the L and the C together was too strong. You can't have one without the other. Lil Mama would have to constantly be in the role of Left Eye which is wrong to me.