Hi, Guest.
There can be no paralel construction if you use "while", since "while" is a subordinator that is introducing a dependent clause. If you wish to use "while" anyway, your sentence could be rewritten like this:
a. "Our primary goal for this site is to provide you with one main communication hub, while promoting a unified identity for the organization."
(you cannot say "while to promote"...")
Without using "while", you could write:
b. "Our primary goal for this site is to provide you with one main communication hub and, at the same time, to promote a unified identity for the organization."
Here, you have "paralel sturctures".
Perhaps there are other ways to improve your sentence. Let's see what others have to say?
Miriam