B.W.
I'd be very leary of putting anti-scar cream on your daughter's lip, because there's no way that it'll sit there without getting ingested.
The other thing is that I've had 2 ankle surgeries. I used the stuff after the first one, cuz it was my first surgery and I didn't want a huge scar. The second time, I didn't bother. And there's no difference inthe two scars. (not that you can compare them, cuz the doc cut thru the scar to do #2 to take out the rod and pins put in to repair the initial break)
She's just about 2, so this is one of the things I would put "on my list" to ask her doctor at her 2 yr check up. Until then, I wouldn't worry about it. Usually young children heal better than adults do, so my guess is that it'll go away -- the other thing is that there might be an infection in there that is low enough down that it doesn't show up unless she smiles and her lip tissue tightens. If that's the case, it'll work its way to the surface. (like a pimple) but see what the doc says.
If it IS a scar and it STAYS a scar, she could probably have plastic surgery when she's older. But right now, if it doesn't bother her, I wouldn't put her through that.