This is supported in 7-mode, but not in clustered Data ONTAP yet.
The way to accomplish this in 7-mode is via the following options:
nfs.authsys.extended_groups_ns.enable
nfs.max_num_aux_groups
nfs.authsys.extended_groups_ns.enable
Turn on the support and set the max aux groups. If your client supports it, it should work fine.
Support for this is coming in a future release of clustered Data ONTAP.