First of all, I regret to tell you that continuing the discussion outside this forum is violating the EE-rules as mentioned
Second of all, as you mentioned >>>i t means that if i install the 8.5 with ip address 192.168.0.200 and later on change the windows server ip to 192.168.0.100 after putting the 8.2 down, it wont cause any problem? <<< there is no problem .or you have another option is to upgrade the 8.0.2 server to 8.5 first then move it to a new machine,,,
http://www-01.ibm.com/support/docview.wss?rs=463&uid=swg21358469Moreover, regarding >>SCM<< if it is configured to relay emails to 192.168.0.100 it will relay each and every email to it no matter what the machine holding this IP address is .
Finally, although I have provided you with the first proceedure of how to create a new OU and what to change but I also recommend you not to do it because you have to apply all the 12 steps on each user document which will be a real though job.