vmdTabs does not change the display of the related products. That is a function of your Virtuemart Theme. What vmdTabs can do is take your related products and put them in a tab. If your related products display is showing the way you want it to show now, then vmdTabs will take that display and put it into a tab.  If you need customization to the related products, however, vmdTabs is not the place for that custom. The custom should be done in your VM Theme.