Hello dlm4001

First when you imported from Marvelous Designer did you import with the option to keep Vert order and Poly groups?

If so in edit mode select the faces you want to add to the group you already have click on the upside down triangle in properties pane and then select the group from the list you want to add the faces to and click on assign. In most likely hood you will probably need to re-UV map your item to account for the new faces you created

Hope this helps good luck

Lobo3433

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