You can only submit one form at a time. Breaking up your document into separate forms will only mean that the much of the data you wish to manage will not be transferred to your CGI processor. A submit button works from within a specific form, and only the key/value pairs of that form are transmitted when that submit button is clicked.

If you are trying to create one big dynamic form where components change based upon the values found on other parts of the page, that's DHTML (Javascript). That's an adventure with a variety of successes and pitfalls of its own.