DMZ *and* DHCP server?

I want to change a network so that I can get DHCP allocated IP's from a
new modem/router, and still route a "base" IP to a server, which then
connects to another router/modem.

The server has it's own DHCP, and also runs ISA Server (which is causing
the connectivity problems with devices such as cellphones and tablets
that have no way of running ISA client s/w).

So like this...

a) Cable modem
..
..
b) (new) wireless modem/router - DMZ to server, small DHCP range for
cellphones, tablets etc.
..
..
c) DMZ IP to server via ethernet - server runs ISA Server, and from the
server the 2nd NIC connects to a modem/router
..
..
d) the modem/router from the server connects to the SBS Server client
PC's via ethernet and wireless.

So this is all setup as above, except for the introduction of b).

Can I make this happen??? I have good granular control over DHCP IP's
assigned by the server, and presumably I could run in the same subnet on
the new b) modem and use a different range of IP's? Or could I use a
different DHCP subnet on b) ???


--
Duncan.