Would fat grafting to upper eyelids help?

That is a nice way of saying that it does not work.  The upper eyelid has many glide planes that need to slip over each other for the upper eyelid to work properly.  Grafted fats scars these planes up.  The more fat that is place, the more one ends up with a scared wad.  Unfortunately, there is a prominent website out there that claims that fat grafting with a fantastic help for this issue.  If only this information were accurate, but it is not.  This site only services to give people a false hope or drive then into the hands of well meaning but inexperience surgeons willing to give this a try.  You have 79 posts, so you should know that there is no substitute for an actual examination by a very experienced surgeon.

Upper eyelid hollowness is a dramatically underappreciated, yet incredibly important component of aging in the eyelids. With normal aging, our upper eyelid fat pads tend to retract and expose this upper lid hollowness, those with “deep set eyes“ are especially prone, and unfortunately old-school upper eyelid surgery that is overly subtractive can artificially create this hollowness early, actually looking worse than it did before surgery - the before and after photo in the link below resulted from overly subtractive upper eyelid surgery with another surgeon, and you can see the results after revolumization of the upper lids. Correcting this hollowness can happen with fat or filler injections into very specific planes of the upper eyelid, or transposing and rearranging the upper eyelid fat pads to provide fullness, as you see in this surgeon’s view video, borrowing the excess fat to move into the areas lacking fullness!
To ensure you are receiving the highest level of care, seek out a modernly trained, new-school dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these “core four” cosmetic specialties. Membership in organizations like the American Academy of Facial Plastic and Reconstructive Surgery help to identify a highly trained surgeon.
Cameron Chesnut
#realself100 Physician

Fat
grafting and/or fillers are very useful. They are often
used to reshape the upper eyelid with or without facial eyelid rejuvenation, as
they make
you look more natural and youthful. This should be done in the hands of a Board Certified
Plastic Surgeon or Ocular Plastic Surgeon with expertise in Fat Augmentation.

Yes, either fat or filler injection in hollow upper eyelids/brow region can restore youthfulness to the eyes and face.  I published the first every manuscript in use of fillers for upper eyelids/brows. See link provided. See an oculoplastic specialist.

In the right person, fat grafting to the upper eyelid can provide a very natural, yet dramatic difference in one's appearance. People can often not put their finger on what they change has been, but when looking at older photos, it sometimes becomes evident that the area has changed. Please view the following images on my eye rejuvenation gallery. Patients ##, #12, #13, #27 and #37 are all dramatic examples of what fat grafting can do for the right person. Many of my other eye area rejuvenation patients have a minimal amount of fat placed in the upper lid. The idea is to be conservative and provide a natural result.

A photo would have been helpful to define the issue better. Having said that, fat injection or for that matter fillers are somewhat risky in the upper eyelid/supra-tarsal crease and not entirely predictable. Even in the best of hands and with some luck they would still both have to be repeated. I would wait at least one year from the date of your surgery before making any decision.

has its risks and downsides, including changes with your body weight fluctuations and lumpiness.  Microfat grafting has been done with great early results but there is no reliable long term studies I am aware of.  So it really comes down to what risks are you willing to accept.  Anecdotally, fat has been producing great results but if done improperly, can leave difficult problems to fix.