Migrating Devices form MS to infoblox DHCP. Keep existing client address

[#1]

We are migrating from MS DHCP to Infoblox. Everything seems to be working fine, except that as we migrate devices over, they do not keep their existing leased address and instead get a new address starting at the top end of the range.

Is this normal or is there something I need to configure to allow the infoblox appliance to hand out the same address the client already has?

Thanks,

John.

[#2]

Without reserved/static addresses, why would you want a client to get the same IP?