A superscope is not what you need.
A superscope creates a larger group of addresses for use on a single LAN segment. Use a scope for each different network ID--LAN segment. So, for each remote site create a separate scope.
Let me see if I can explain it.
A scope is for a range of network addresses; be it all the addresses of the network ID or a partial range of them. When you exceed the number of available addresses, i.e 254 addresses in a class C network, you can create a superscope by adding another network ID to the first network ID and masking it to look like one network ID. By masking the 2 class C networks, you can create one larger network of 510 addresses.
The problem comes when you introduce a router into the picture--as in your case. By nature, a router will not forward broadcast from one LAN segment to another. This is why you need a relay agent or a bootp forwarder.
A relay agent is created on the local segment (network) and listens for DHCP specific broadcasts. It converts the broadcast to a unicast and sends it to the programmed DHCP server directly. The DHCP server notes the relay agents address and determines the network ID of which it came from and serves an address from the proper scope.
On the other hand, a bootp forwarder is an early version of relay agent. It is a configuration on a router that tagged and passed the broadcast onto the next segment. Eventually it got to the DHCP server and the server would see what network it had originally started from and issue a proper scope address.
One of the problems with bootp forwarding, depending on the hardware on the network, is that every device hears this and sometimes you would end up with multiple DHCP requests from the same device going to the DHCP server. This created more network traffic, all broadcast based.
I hope this helps.
bob