A: you DONT modify your TM backup, youd just add files into the same HD, however thats no good because........
Youre trying to create a nasty choke point for data failure by putting time machine AND your files on ONE DRIVE, 😟
very bad idea, hard drives are cheap as dirt, buy another, 2 MINIMUM external redundant backups of your vital data, period.
also, cloud isnt a place for data archives, and not safe, not secure.
The Tragedy that will be, the tragedy that never should be
Always presume correctly that your data is priceless and takes a very long time to create and often is irreplaceable. Always presume accurately that hard drives are extremely cheap, and you have no excuse not to have multiple redundant copies of your data copied on hard drives and squirreled away several places, lockboxes, safes, fireboxes, offsite and otherwise.
Hard drives aren't prone to failure…hard drives are guaranteed to fail (the very same is true of SSD). Hard drives dont die when aged, hard drives die at any age, and peak in death when young and slowly increase in risk as they age.
Never practice at any time for any reason the false premise and unreal sense of security in thinking your data is safe on any single external hard drive. This is never the case and has proven to be the single most common horrible tragedy of data loss that exists.
Many 100s of millions of hours of lost work and data are lost each year due to this single common false security. This is an unnatural disaster that can avoid by making all data redundant and then redundant again. If you let a $60 additional redundant hard drive and 3 hours of copying stand between you and years of work, then you've made a fundamental mistake countless 1000s of people each year have come to regret.
