This is my part of town is the English idiom
That's true. If they didn't accept it, that's probably because they wanted to stress the fact that byen is in the definite, so they want us to put "the town" or "the city".
Why not share?
Denne by er ikke stor nok for de to af os
Why is it dette? Can someone remind me those forms of this/that in Danish?
Denne / dette / disse - this (fk) / this (n) / these
Den / det / de - that (fk) / that (n) / those
If you have a clause saying "it/this/that is", you use the neuter form, no matter the actual gender of the noun it refers to.
You must be quite a rich girl, aint ya.