Link forms to base

When I create a form is there a way to link it to an already created base?
For example I have a CRM base. Many of the client info is already in the base but now I want to add birthday and mailing address? Can I link the form so they can input the info but it populates the already created record?

Rephrased: Can a form view edit an existing record? The answer is no.

miniextensions.com makes a common third-party extension which provides this capability.