Lets say I have a very complex drawing that will take very long to redraw in new part. How can I copy it to a new file keeping all dimensions and relations. Every time I do copy and paste from black drawings goes white and dimensions get all screwed up
If the old part and new part are similar, and I assume they are, I would recommend doing a Pack and Go of the original drawing, and change the names of the new drawing and part during the Pack and Go process. You could then make whatever changes needed to the new part, and all dimensions and associations between the new part and drawing should remain, except of course for those lost due to any changes made in the part.
Mukesh' suggestion may also work well, especially if you've already made the changes to the new part.