help in database design

hi all, i need help in design a database, our office is hospital equipment supplier, we had a list of items, each items had it's own configuration, and each item could consist of several item. we also had contract that have a lot of site, sometimes equipmend that have been ordered different from what the site received, in that case we made a change request... for now we have this |contract|------|has|-----|site|

                      |
                      |
                  |item|----|material|
                      |
                      |
             |configuration|

but i really confused about the Change Request thing, we have to keep both what have been ordered and what have been received... where should i put it, sorri for my bad english tq -- Jangan tanyakan apa yang Indonesia telah berikan pada mu tapi bertanyalah apa yang telah engkau berikan kepada Indonesia -----BEGIN GEEK CODE BLOCK----- Version: 3.1 GU/IT d- s: a-- C++ UL P L++ E W++ N* o-- K- w PS Y-- PGP- t++ 5 X R++ tv b+ DI D+ G e+ h* r- z? ------END GEEK CODE BLOCK------