Though Nefertari is by far Ramesses II's most famous queen, Istnofred (Isisnofret) had considerable importance within the court. She was, early on, the second principal wife, and may have been closer to Nefertari in importance then what we know. It is very possible that the two queens had similarly important responsibilities, with Istnofred domain being northern or Lower Egypt.
While there is little doubt that Nefertari was probably Ramesses II's favorite and most powerful wife, it was Istnofret who bore Ramesses II his most important sons, including his successor, Merenptah, and the well known and loved Khaemwese, High Priest of the Temple of Ptah at Memphis.
Furthermore, after the death of Nefertari, Istnofret became Ramesses II's "Great Royal Wife", becoming his chief queen. We believe this was in year 24 or 25 of Ramesses II's reign, and she remained his chief wife until her death. We are not sure at what point she died. Perhaps she lived less then ten years after the death of Nefertari, but we do know that she preceded Ramesses II to the grave. Istnofret's tomb has never been found, though it is probably on the West Bank at Luxor.