Multiple forms for one content type using one module I want to create the following functionality:

Multiple interrelated forms needed


Form 1, 
Form 1 detail and
Form 1 user detail


But the user can fill in the forms only in order.. I mean when the first form is not inserted then the detail and user detail form aren't available to the user.. and additionally I want to relate those forms also.. 

Is this possible with just one content type? Any ideas how I can achieve this in Drupal 7?
You can use drupal Webfroms for this purpose.

Webform is the module for making surveys in Drupal. After a submission, users may be sent an e-mail "receipt" as well as sending a notification to administrators. Results can be exported into Excel or other spreadsheet applications. Webform also provides some basic statistical review and has and extensive API for expanding its features.

Some good examples could be contests, personalized contact forms, or petitions. Each of these could have a customized form for end-users to fill out. If you need to build a lot of customized, one-off forms, Webform is a more suitable solution than creating content types and using CCK or Field module.

here is the way you can create a multi step form which solves your purpose