A Volume Group ( VG ) consist of 1 or more hdisks.

A VG holds 1 or more Logical Volumes (LV). which hold normaly a
Filessystem ( FS)

So for your problem:
Find out the name of the VG which contains a FS that is mounted as /d3

# lsfs /d3 | tail -1 | cut -f3 -d"/" | xargs lslv | grep GROUP

You will see something like:
$ LOGICAL VOLUME: lv01 VOLUME GROUP: datavg

Now check if you have enough free space in that VG
# lsvg datavg
and look for .... FREE PPs:

If yes:
# smitty chfs
and use the VG name where to place the new FS.

If not: Reduce the LV which holds /d3 - but this is another story wich
depends pretty much of your OS level.

Also i still hope that you do not use an old smitty on an old SUN
machine because your writing sounds to an SUN Admin.

hth
Hajo