Sharepoint Discussion Board

Hi, My task is to configure sharepoint 2010 discussion board.

I have changed creation and editing forms with sharepoint designer. The hardest task is to change redirection of the "Save" button in the form. I found some javascript functions to change redirect url like

<input type="button" value="Save" name="btnSave" onclick="javascript: {ddwrt:GenFireServerEvent('__commit;__redirect=)}" />

But I should make redirection to the message on which we make the answer, and this is the problem.

In the default reply form URL we have all we almost need, and the parameter: "DiscussionParentID" type of int.

To redirect to the message we need the url should consider something like this: "#{8421BC8B-3F24-4EB5-939E-32726BEE4E09}"

My question is how we can find the GUID of the parent message? all we have is DiscussionParentID.