Since I am a little nervous about erasing Mavericks from my external HD before I put it back onto my internal HD with the steps you gave me, here is what I am thinking:
(I have no real experience with Time Machine so I'm not clear how to do this)
Would it make sense for me to back up my HD (actually my external hard drive if that makes sense) with a Time Machine backup on my third partition called Misc that already exists and is empty? Then I could try to restore my internal HD from that copy and not worry if it doesn't work because I still have my Mavericks partition to use should something go haywire.
Also, I went to T/M and chose "options". A window came up that said "exclude these items (Mt. Lion and Misc) from backups." Nowhere does it even mention Mavericks which I am using as my start up drive.
So, I'm not sure what steps I take to B/U my ext. HD with T/M onto the misc. partition so I can try to restore it to my HD.
I am not doing this until I get my new computer but I want to be prepared. I am dreading learning a new OS which is maybe why I haven't ordered it yet.
Your opening statement doesn't compute; if you erase Mavericks from your external HD before you put it back onto your internal HD you'll have nothing to put back.
It never hurts to have another backup, so TM (Is your destination partition sufficiently large?) is a good idea; a TM restoration may even be a more desirable way to get Mavericks back onto your old MBP's internal HD than cloning. (I still recommend erasing the HD first.) But I'm not the guy from whom you want to get TM assistance; I haven't even got it on my MBP. (If nobody picks up on this thread you can start a new one.)
And then again, you can forego the Mavericks restoration and restore or clone Sierra to your old MBP after you've got your new one up, migrated, and running.
