We have recently changed our ip address range from a 200 network to a 172
network. I have created all the necessary subnet pools and ip ranges for
the new 172 ip address but my question is how do I get the DHCP server to
start using the new 172 range without removing the 200 range just yet.

I want to make sure that everything is working fine with the new range
before I remove the old range.

Any assistance would be great.