How to force a client to be a member of a specific IP address range boundary

Hello all,
 
I have setup a new SCCM 2012 site side by side with our production SCCM 2007 site.  Everything works except site assignment when deploying the Configuration manager client.  I know this is due to overlapping boundaries and because of this the client is seeing the old site code.  Both sites are set for an IP address range covering our entire subnet.  I want to set it up so that there are two separate IP address range boundaries, one on each the old and new server.  My question is, how do I make new clients only obtain addresses in the range covered by the new SCCM2012 site boundary?  My hope was that I could have an OU that had the new SCCM GPO attached and move clients into that OU as I wanted them to upgrade to the new configuration manager client.  I just don’t see a way to have the clients become members of the new boundary based on their IP addresses, allowing them to only see the new site code. 
 
Any help would be greatly appreciated.
 
Thanks
 
Roger

You can't.  A client will get any valid IP from DHCP that's offered.  So if you cannot segment them, you could just use a forced assignment for the new clients instead of AUTO.  If you didn't share sitecodes, that'll work.  And a CM12 client will never assign to a CM07 site.

Got it.  Thanks for the reply.  Guess I'll just do all my testing with a new boundary and assign my test clients static IP's within that boundary.  Then, once I know everything is working, I'll just remove the boundary from SCCM 2007 and add it to SCCM 2012 and then add the boundary for the full range to 2012.  I just wanted to be sure there wasn't another way.  Thanks again!

When you say forced assignment instead of AUTO, do you mean deploying using the client push install with the SMSSITECODE option pointed to the new site versus the "Software Update-Based client installation" that I have been doing?  Does that work independent of site boundaries? 
Edit: Or are you meaning force the assignment of the CM12 client from CM07?  I did use different site codes.

I meant use SMSSITECODE - you can set it in the client install properties if you push, or you can just go to the one PC and force enter the sitecode on the discovery tab.