Hi TMADOCTHOMAS,
If you wish to use Igroup with the custom naming convention, you can create it on storage (via Cluster shell or System Manager). In SnapCenter, you can select the already existing igroups by selecting the second bullet option. Just type in the first few letters of the igroup name and it will auto list the igroups from which you can select the required one. By the way, mixed type igroups doesn't cause any issues as such.