not at all, at least in this RP. like you can say you were a machine built by Viktor, am upcoming rival inventor of Jayce in Piltover, etc. Often i find though the loose the connection is, the better. Across all plots, an apprentice of Vlad would make you Noxian, more than likely. I have a hard time seeing Vlad take on an apprentice as he has such a superiority complex, however, this student could possibly have show exceptional potential.
Zac will be a viable playing option, once we know more about his kit. Some skins also, depending on the plot, i may let exist as their own character. I.e. Ez vs pulsefire ez, Varus vs Arclight Varus, in otherwords, skins that tie into the lore still, but have an almost separate character all of their own.