What is the proper procedure to backup to multiple external hard drives if one wishes to rotate drives such that you may store one in a fire safe?

Question

Description:  If I want to back up to two external hard drives using Time Machine, what is the proper procedure to follow such that I could keep one attached to Time Machine for daily backups, and one that I attach monthly such that I can back it up monthly, and then store it in a fire safe.  To do this, what are the exact steps to follow?
Research in Progress:
I selected the "?" icon in Time Machine which took me to "Mac Help - Time Machine Preferences" section.  I reviewed this section, including the "Select Backup Disk, Select Disk, Add or Remove Backup Disk."  It says, "If you haven’t set up Time Machine, click Select Backup Disk to set up a backup disk. Repeat the steps for each backup disk you want to set up."  I did add two backup disks.  It goes on to say "If you already set up Time Machine, your backup disks are listed, and information about each backup disk is shown. To select, add, or remove backup disks, click Select Disk or Add or Remove Backup Disk."  Well, what is lacking here is what happens when you "Remove" the backup disk.
As I have read this section, it raises additional questions:
What are some cautionary statements.
What happens after you remove a backup disk?  Will Time Machine recognize it later?
What is the proper procedure for removing and ejecting one of your external hard drive when you use it with Time Machine?  What happens if you don't "remove" a backup drive and instead just drag it to the "trash can, i.e. eject it" and later reconnect it.?

Answer 1

Time Machine supports multiple backup drives including network area storage volumes (NAS) as well as physically-connected external backup drives.
In , System Preferences, Time Machine, add the second drive by clicking Select Disk.
All available connected drives including connected network drives are displayed.
Select the additional drives, one at a time.
Connected Network drives are displayed on the desktop only when actively being used by Time Machine for backup.
When prompted, select 'use both' when adding the second drive.
Then choose Select or Remove at the bottom of the list of available devices and network volumes to add additional drives.
Time Machine then automatically rotates backups among the available designated devices and volumes.
If the drive is physically not present, Time Machine skips to the next available backup drive.
To DISMOUNT a drive to take it off-site, it is NOT necessary to remove it from the Time Machine preferences.
When the drive is NOT in use, dismount it by Command+clicking that Drive icon on your desktop (or in Finder) and then "Eject".
That's it.
After 10 days with no backups to a given device, Time Machine does display a message and (as I recall) asks if you want to remove that drive from the rotation.
You can never be too rich or have too many backups!