I assigned a 2nd mesh to my vertex group, but it doesn't move with the group

My character was animating just fine.
The parent bone of all the other bones is called “body”, and has a vertex group of the same name.
Additional ornaments were needed, so I created a new mesh and assigned it to the vertex group “body”. (The new mesh also has its own vertex group “proboscis”.)
I expected the new mesh to move along with the rest of my “body” vertex group, but it doesn’t move at all.
Can anyone tell me why?

The new mesh object needs to have an Armature modifier on its stack pointing to the rig with the “body” bone.

You can skip this step IF the new mesh is not deformed by the rig that has the the bone “body,” by making the new mesh a child of a particular bone in the rig. For example, for an item that rides on the character’s belt, you might make the item a child of the bone that controls the pelvic/hips region. Select the item, select the bone (armature should be in Pose mode), use CTRL+P to Parent, then choose “Bone” from the options in the pop-up menu.

When using a bone for parenting a mesh, you don’t need a vertex group named for the bone, or any vertex weighting for that bone. Those are only needed when the bone will deform the mesh from its base shape.

Thank you kindly for your quick response. I am afraid that I expressed myself poorly when I described the issue. I have only one Mesh object in my whole project, and I added new vertices to it using the Add -> Mesh -> Circle menu options. I didn’t actually add a new mesh.

I found the problem by using the ‘N’ key in the 3D Viewport window to call up the Transform Properties window. Comparing the group memberships of vertices that were moving properly to my new vertices, I found that my new vertices were part of the ‘body’ vertex group, but not part of the ‘all’ vertex group which was the vertex group that the Armature modifier had dominion over. The Armature modifier had the property VGroup: all. When I assigned my new vertices to the ‘all’ group, they moved with the rest of the mesh.

Thank you for the tip about parenting non-deforming meshes, though – I can see how that would be very handy.