Is there a way to create multiple URLs that point to same website form?

You could use a URL parameter that feeds into a hidden field. For example... http://yourwebsite.com/your-webinar?webinar_source=partnerA

And then in your form, you'd create a hidden field that pulls its value from the URL parameter "webinar_source"

All you'd have to do is provide your partners with the URL with their specific parameter. Does that make sense?

Totally agree with Matt. I actually like to use a triggered campaign to dump people into "tactic programs" when they fill out the form. Depending on what they have in their querystring when they fill out the registration form, I dump them into one of these tactic programs so I can always see how many registrations have come from each promo source.