Can i include external usb drives in Time Machine backups

Question

Can I include external usb drives and sticks in Time Machine backups?
This was the question I searched a week for. My machine is a MBAir with Yosemite. I have a bunch of USB HD and sticks. This is a sharing of what it took to solve. I lost a couple of important document revisions lately because of not having differential backups on them, so wanted to include them in Time Machine.
Yes it can, I found. But it's a wee bit backwards. And apparent inconsistencies drive you crazy. Time Machine is supposed to do this by default, and wants you to tell it what NOT to include. Trouble is, formats create many troubles.
But the USB sticks and HD's you buy are PC formatted. And you'd like to share, as the Apple does with FAT16, FAT32, and exFAT (to overcome the 4G size limit on the others). Even NTFS can be plugged in and be read-only. Turns out you just can't incorporate into TM backups.
Open Time Machine Options, and look at the drives listed in the exclusion window. Drives that you know to be plugged in and registered by Finder, may or not be registered in the exclusion window, and if registered and their icons may be bright or dimmed. Bright will NOT be included. Dimmed are excluded. Normally the operation is to use the or to exclude these drives from your next BU operation. (this instruction is lost the next time in manual mode). So if a drive or stick is shown and is bright it WON'T be backed up. If you it from the window, then it will grey out and WILL be backed up. If it's not there to offer you exclusion, you can browse to such a file or device so you can exclude it. TM's exclusion window will show the PC formats: FAT16, FAT32, and exFAT greyed out (as not included). NTFS is bright looking like it might work, but when    doesn't dim, it disappears, and is ignored in the actual BU.
Sources are supposed to be included in the backup if it isn't shown bright in the exclusion window. In this respect I only use TM manually, and not for programmed BU's, so I cannot speak to that.
If everything you have is formatted for the Apple disc system (Mac OS Extended) then there are no contradictions or partial equivalences. The mounted disc or stick will show in TM exclusions window, and if you it, you'll see it in the Time Machine pile of calendared directories, with all the files. And of course it will do the differential backups for it that we use TM for in the first place. Just remember to prepare the BU by not excluding.
BUT NOW THE VARIABLES. It now depends upon the formats. I use the Paragon NTFS program to permit writing NTFS. (Apple can normally read but not write NTFS). Paragon is lovely because for normal computer use, I can read and write both Apple and PC files and disc formats in Finder (for 3 years now). But Time Machine cannot be reached by Paragon so it's NTFS behaviors are outrageous. Paragon reaches Disk Doctor so you can read, write, format and heal both Apple and PC formats. And this really confused things respecting Time Machine. I literally worked through every variable, from stick to disc to prove what did work, and when false appearances of working showed up.
Respecting that very Time Machine display of Finder windows piled backwards through time there's a confusing bug. When first opened, TM shows NOW as the current setup and works just like a Finder window in present time. And the outboard discs and sticks show as in Finder. BUT working back in time, the left window DOES NOT SHOW THE CONDITIONS AT BACKUP but rather in all left windows shows the present setup. So you need to work from the right hand side dates and times to go back and see when you had that stick or HD plugged in. And then, finally, you will see the files you wanted saved. But if there is a stick on the left than TM doesn't like but Finder likes you'll see it left but nothing will be in the files. Clicking on the pretender just jumps to the root.
My Disk Doctor provisions (with Paragon) show, Mac OS Extended (Journaled), Mac OS Extended (Case Sensitive Journaled), MS-DOS (FAT), exFAT, Windows NT Filesystem, Windows NT Filesystem (compressed). It's a better utility than in Microsoft and I use it for such maintenance.
Bottom line, I like TM very much. 2 years ago I lost my air and TM was able to reconstruct my machine many times in the course of the troubleshooting - all the way from the start to the last without ever missing a beat or a file. So I accept this limitation and make copies to another HD formatted in NTFS when I work on PCs.
Hope's this sorts out being lost in the desert for a few of you.
Jock
<Personal Information Edited by Host>

Answer 1

Storing normal data files on the Time Capsule is unfortunately not as easy as dropping the folder on the Time Capsule.
Open up Macintosh HD on the Mac
Look for the SHARED heading on the left
Click on the Time Capsule icon and a folder named "Data" will appear (unless you have renamed it)
Double click the "Data" folder to mount the drive on the desktop. You may need to enter the device password for the Time Capsule when you do this the first time
Once the drive icon is on the desktop, you can drag data to the icon and drop it there. Double click the icon to open up the drive and see the files