MVC :: Retain Partial Data In Model Over The Post Backs?

I have recently started learning ASP.NET with MVC 2 Framework, I am facing difficulties in the following scenarios.In my MVC application I want to retain partial information in Model over post backs.Following is my scenario,

1. I initiate "Edit" of main record by clicking date hyperlink from left navigation.

2. Amend some data.

3. Save the record.

4. "Edit" sub record of the saved record by clicking another hyperlink from bottom left navigation panel.

The page is divided in to 6 tabs, the first 5 tabs shows the data for the main record and the 6th tab shows data of sub record. Wehn we "Edit@ sub record the previous 5 tabs doesn't have any changes noted, that means there is no harm in keeping their details intact in the main model. So is there a way to access model in the controller on hyper link click action so that I can only load the data for the clicked sub record (I am asking this, because the hyperlink click uses HTTP GET method so no model parameter passed in action method). If no, then how do I retain partial values in the Model over post backs?

Note that each tab data have been kept in individual models, and a main model has a collection member to hold all these individual models together.I thought as the model is binded with the view, it is too binded with controller. But it is allowing easily to access model in variable "Model" for the view but not for the controller.