Hello, Dr. George Abrahamian MD here, from La FUE Hair Clinic, Pasadena, CA. When it comes to hair transplant revisions, there is unfortunately no broadly accepted guideline to use, and is typically evaluated on a case by case basis. Once the graft is implanted, and has taken root, the only ways to permanently get rid of them include using an FUE punch to remove the hair (which will likely leave hypo-pigmented micro-punch scars, similar to those seen in the FUE donor area), or electrolysis/laser hair removal. However, since most people do not want to have FUE punch scarring across the forehead/hairline, or to lose the hairs that were originally grafted via laser hair removal/electrolysis, a supplementary transplant can be performed to help blend the newly transplanted hairs at the appropriate density and angles, with the previously misaligned grafts. A revision of a transplant is always far more difficult to perform, but is definitely doable, as long as the donor provides the necessary amount of grafts to be able to perform the revision. The best advice that I can give anyone considering hair restoration is "measure twice, cut once". Hair transplant surgery will be on your face/head for the rest of your life, so doing it right the first time is paramount to achieve the look you are going for. Make sure the clinic you are considering for repair has an expansive portfolio of before and after photos, and that the clinic has a clear plan on action for how they will be handling your individual case. I hope this helps, best of luck on your hair restoration/repair journey!