[Borgbackup] suggestion append data for existing archive

[Judith Brown]

If am searching for a backup + optimal solution to raspberrypi media management.
Assume I have a (2TB) large /media/SOURCE and small /home/pi (~8GB from microSDcard).
I do a first backup:
borg init /media/2TB_BACKUP
borg create  /media/2TB_BACKUP::archive-1  /media/SOURCE

Now, I mount
borg mount  /media/2TB_BACKUP::archive-1  /media/DATA

I remove 2TB /media/SOURCE
Now I mount a small 8GB usb stick at /media/SOURCE

My suggestions:
1. If I run (with 8GB usb stick)
borg create  /media/2TB_BACKUP::archive-2  /media/SOURCE
this archive will have only the NEW 8GB data. 

2. Can I access *all* data from archive-1 + archive-2 at the sametime at the same mountpoint?

Instead of (1), it would be great if there was a 'append' parameter, so that I can 'append' data onto the archive-1 thereby while 'creating+adding new data borg does compression+dedup. This after initial setup I can make /media/2TB_BACKUP and make it my main  'disk' since it features deduplication and compression! (onto any filesystem - like ext4 or XFS).

I wouldn't mind umounting eachtime before running a 'append'. Do you think this qualifies as a feature for future? Thanks for the great work.