IP Group Nesting

Need the ability to nest IP groups, for example:

File Servers

                Windows File Servers

                AFS File Servers

                NAS File Servers

Application Servers

                Application 1 Servers

                Application 2 Servers

                Application 3 Servers

IP Groups could be created with overlapping entries; however any addition or removal of an IP address would need to be done multiple times, resulting in the groups getting out of sync over time. Nesting should be supported at least 3 levels deep.