When someone fills out my webform, I have a hidden field with "Website" as the Lead Source.  But suppose I buy a banner ad on SomeDirectory.com.  I will want to send people to my website but I want the Lead Source to come though as SomeDirectory (or some other value) instead of "Website".

Is it possible to pass the Lead Source value through the URL?  Such as abc.com?leadsource=SomeDirectory or pass a UTM value as the lead source?

I would want the value in the URL to overwrite the value in the webform.

Some will say "create a different lead form" but I have one signup page and based on the product I sell, that is all I need so multiple signup forms would not work for me.

Suggestions?

Thanks in advance.