Nested MasterPage - The Content page doesn't load first

Hi.
I have a fairly simple structure with a masterpage and some content pages. I have some code where I take advantage of the fact that the content page is loaded before the masterpage. However now I have decided to have a parentMaster page, where the original master page is its contentpage. Like this:
                                     ParentMaster.mater
                                                   |
                                     Masterpage.master
                                      /           ...