Custom User/Group Grants in Perspective

We have a project that uses AD as user source . there we have groups like Engineers, Operators,…
We also have some(18) non-role based AccessLevels/Functions that we would like to assign to some specific user groups. we have defined these 18 functions as custom level under authenticated. We know that using user grants we can assign custom levels to a specific username ; Is there a way to assign a custom level to a group/role instead ?