DHCP static leases in a single go

So far, at adding a new device, the usual steps are DHCP on the client, followed by Set Static.
This isn't actually how I do it, however. Because I follow up changing that static IP, in this moment quite random, to a specific range allocated (in my head) to a group of users, single user, type of resource.
Until now this is quite cumbersome: going to static addresses, selecting one, pull down the existing ones, this includes the newly associated MAC, but it is not editable. So I have to go down further, and start typing the address that I want to allocate from scratch.
It would be much less hassle, if Set Static immediately showed the freshly given out IP as editable field.