We recently submitted a paper to ECCV (European Conference on Computer Vision), but realized after the submission deadline that one of our significant contributors was omitted from the author list. ECCV's policy states no changes to authorship are allowed after submission. However, this person made substantial contributions to the work, including coding (with Git history as proof) and ongoing project communications, with every kind of proof that you can think of.
Given the importance of ECCV in our field and the extensive work required for acceptance, are there any circumstances under which conference organizers might consider adding a missing author? What are the potential consequences of requesting such a change? How should we proceed in this situation to ensure proper credit while adhering to conference policies?