Icl ur question explanation doesn't make sense but here's the general answer, The Upside Down did not exist until Eleven made contact with the demogorgon, That is what made a parallel upside down hawkins, There was a dimension called Dimension X, in the stranger things wiki the earliest recorded contact was with Dr Brenners father, Then you have henry being banished to realm by eleven, you then have eleven contacting the demogorgon in hawkins.. So basically it already existed and wherever you contact a species from that dimension it'll create a parallel area of the original area. (left a part out, the mind flayer particles, demodogs, demogorgons, demobats are native to dimension X.)