Where to inject fat for nasolabial folds? And can fat be injected into the glabellar to decrease the fold between eyebrows?

There are a number of considerations when addressing nasolabial folds
prominence. Sometimes the amount of skin excess  is such that adding
just volume is not sufficient for an adequate correction. A facelift operationwould be indicated and volume replacement may be performed at the sametime. Another consideration is how much volume loss of the cheeks is present.
This can also affect the nasolabial folds appearance. An evaluation by a board certified plastic surgeon experienced in facial rejuvenation is recommendedto discuss your best options and risks. Best wishes.

After over 20 years of facial fat grafting, we can say that it doesn't work when place in nasolabial folds. There is some improvement when placed superficially in glabellar area in combination with Botox; nano fat grafts (stem cell suspension) perform better in glabellar area but not in NLF. We use fillers for correction of NLF. It is likely that  constant movement of this area (speaking, chewing) is responsible for poor take of any grafts.