The upper and lower lips have many subunits, which are named for their geographical location. You have lost the "cupid's bow peak", which is the central part of the upper lip. Use old photos, taken before your intial surgeries to communicate with your surgeon your aesthetic ideals but be prepared to have staged reconstruction. During the course of burn reconstruction, we often have to reconstruct the upper lip with tissue "borrowed" from the lower lip, a process called an Abbe flap. Hopefully you wouldn't need such a drastic procedure, but without seeing a current photo, it's difficult to exclude it absolutely.
Removing the Alloderm is possible, but you will need not only tissue of adequate volume but also color. It's possible that you will need micropigmentation or tattooing of the area, after the surgical aspects are complete. Good luck.
