Using LR Classic, copied LR catalog to new disc, how to locate missing files in LR on the new disc without doing it one folder at a time?

More Info…  SSHD with original DNG has 175,000 images.  LR Folders panel sees 3800, because those are the folders that I have reconnected by hand.  How do I get LR to connect to the rest of the images on the SSHD.  There has to be a better way.  It will take forever this way.  

More info… I have done this before and not had this issue.  I am missing something.  In the past, I feel like I reconnected 1 folder and LR was smart enough to know that all the images were on this new HD.    🤔.   To simplify… How do I get the LR catalog to find the new HD of original images in one (or 2) steps?  Tried the”Find all missing files” route but then what?  It directs me to the ext HD which has 175,000 images on it.  The same HD within LR only has a little over 1,000 images.   How do I show LR catalog to see the entire ext. HD of original RAW files?   What am I missing?  TIA.