Merge two Catalogs

I plan to merge two catalogs in LR, each is on a seperate drive. I will be installing a new hd just for photos and I want to go back to one catalog. Should I start a new Master catalog, import each previous catalog into this new Master while moving the images to the new hd? Also,will each preview data lrcat  move when the catalog is merged into the new one?  Suggestions please.  Thanks..