Quote - If I alter the model in my other program and then export as OBJ again into Vue, of course the model will be back to the original size and postion again and I have to start up with resizing it and re-positioning it.  That is why I freeze the model design at some point and only make minor adjustments to it once it is imported into Vue and I don't go back to the original model again.

I reread my post and I see worded it wrong. I now see it sounded like I imported the roof separately, but the roof and walls were all imported at the same time so that's where the confusion came in. I never alter the model without exporting all parts again. Sorry for the confusion.