Copy/merge weights in vertex groups

Hey all!

A lot of vector programs have a merge down feature to mix layers. Blender, however, has no means, at least as far as I can find, that will allow you to copy weights from one vertex group to another. It will allow you to copy vertex groups and transfer them between meshes, but no way to merge groups or copy weights.

Origin of the idea - I created a character and he needs to have two sets of hair. One that uses displacement for wind (different groups for different waves). BUT, the united one with the hat, all the groups need to be unified - no means of doing it. I think only by unparenting and making sure they are named the same, will merge them, which is not very practical, lol.

Let me know if you have ever run into this issue with weight painting, lol.

Poses can be copied and pasted, even reversed, but no weights.