two domains to a single wordpress blog on different points

Hey, i’ve been googling and testing for over 2-3 h now and could not find a solution and don’t know for what to google now 😉

what i want to do is: have one wordpress site and point two domains on it. the maindomain.de -> goes to the start page and the specialdomain.de -> should go to the special site in the menu. but the best would be if the click on the spacial menu entry goes also to specialdomain.de

so i would like to have a structure like

– startpage (maindomain.de)
– – blog
– – page 1
– – page 2
– – special page (spedialdomain.de)
– – – special child site
– – page 3

the layout and menu should be the same on every page, but the klicks on all pages under the special page should use the spacialdomain.de and if i’m on a special site and klick on blog or any other site i will go back to the maindomain.de.

i’ve tryed a multisite installation with multi domain mapping, but i have no posibility to get the page tree from a other site in the maindomain.de site, or?

don’t know if it’s clear what i would like to do…
any questions or suggestions?

greetings
jan-victor