You want to perform daily backups of your machine: a full backup each Monday and incremental backups on Tuesday through Sunday.
You want to back up to the archive MyMachine on an external hard disk drive.
You have two such drives. Either of them has drive letter D in the operating system when attached to the machine.
You want to swap the drives each Monday, so that one drive contains backups of the current week (Monday through Sunday), and the other drive those of the previous week.
In this scenario, you need to create two backup plans as follows:
When creating the first backup plan, specify MyMachine as the archive name and D:\ as the archive location, select the Name backup files using the archive name... check box, select Full as the backup type, and schedule the backups to run every week on Monday.
When creating the second backup plan, specify the same settings as in the first backup plan, but select Incremental as the backup type and schedule the backups to run every week on Tuesday through Sunday.
Result:
Before creating a Monday backup (by the first backup plan), all backups will be deleted from the currently attached drive.
While one drive is attached to the machine, you can keep the other drive off-site for extra data protection.