While IPAM does allow parent/children mapping, it does not allow supernetting. The difference is a supernet would represent a visual hierarchy without being an actual network. e.g.
Supernet: 10.0.0.0/8 - cannot assign IPs
Subnet 10.1.0.0/16 - can assign IPs
Subnet 10.2.0.0/16 - can assign IPs