Accessing variables of multiple masterpages from content page

Question

To access the variables in masterpage we use the MasterType directive:

<%@ MasterType  virtualPath="~/MasterPage.master"%>

In my new project I have a master page that has 3 other master pages as its content pages and each of these master pages has many content pages. Now I want to access the variables of both master pages from the content page (the master page of the content page and the master page of the master page).

Any idea how this could be done?