It's very very difficult from photos under these circumstances but it kind of has the general look of a mystic or phantom. Tram lines are often a red herring and only really come into consideration when it is a known pied clutch
Update: The previous owner paired it with a pied and one of the hatchlings was a pumpkin pied. So, proven yellowbelly. Proven het pied. Still looks like there might be something else there... Weird.