Ouch.
You can't have more than one Solaris/Solaris2 partition. It might make your system unbootable.

Set partition 2 type to something else and create a ZFS pool on it if you are running Solaris 10. If you aren't, you can create a ufs partition on c3d0p2 but that's not straightforward.

Edit: just noticed your root partition is on ZFS, so you are definitely using Solaris 10u6 or Solaris Express, so just create a ZFS pool and you are set.