It might be a bit to late. but it is posible to take the origanal with the good uv's. cut off the parts that were/will be changed. Import the obj from light wave.. cut out the changed parts you want off the new altered object... UV map just the changed parts.. make sure to move the UV's out of the way in texture space on the edit object, of whare the origanals will apear in the map. Combine the poly objects. Now both UV's should apear on the new single object, merg the edges, sew UV's togather. Its still a bit of work, but if you have a lot of time and work in the UV's it can be very worth it.. try it out with a simple ojbect first to get the hang of it.