Ability to start scheduled incremental backup before te previous backup is completed.

We are running certain policy backups every 4 hours. The partition contest is permanently changing. The files older than one day or sometimes older than few hours can be purged and totally new files can be created on the same partition. The size of the partition is ~800 GB each. If one partition backup is running too long due to size and/or performance issue, the other partition backup can not be started until all partition backup is completed.

For example, we have three partitions on a client: /one, /two and /three
The parent job starts at 12:00 AM. All three partition backup is scheduled and started to run.
By 4 AM /one and /two backup is done.
But /three is still running for another 24 hours.
The new backup for /one and /two partitions will not start till /three backup is completed.
And the files which were created on /one and /two within 28 hours interval may be partly deleted.

I think it is necessary to start another parent job for the same client at 4 AM for all partitions which backup is not active or queued.
In the above case only the /one and /two partition backup should start running at 4 AM.