I had a 2013 MBP Retina that I have been doing regular Time Machine backups to an external hard drive. A few months ago I also bought a Mac Mini which I just started from scratch with, and never transferred over any files from the MBP. I was using both, simultaneously for somewhat different purposes. Well, my MBP stopped working (probably logic board according to my "Genius") and I don't feel it is worth the price to fix it, and I am not able to afford a new laptop right now. So what I want to do is restore my MBP backup onto my Mini, without deleting what is already on it, OR merging the two. If I create a new user on my mini, can I restore my backup to that user profile only, leaving my original user information intact?
I don't have a categorical plan of action to manage this strategically from soup to nuts, but based on once when I accidentally migrated the same user onto an already fresh install, here are some ideas.
First. Ensure you have solid backups of both, in case things get out of hand.
Migrating onto an already set-up Mac will generate two separate accounts, even if they have the same name. Unpicking this by hand is not a simple job.
If you want to, for instance, merge the email databases, I don't see any method to achieve this, however, anything already synced over iCloud should already be merged.
If all you need to do is cherry-pick files from one to the other, I'd do it manually.