Create just one backup without date on the name

Is it possible to create a backup folder without date and _number on Name with btrbk ? (just todo a sync folder)

Explain : I have 3 HDD : hdd_master, backup1, external_backup2.
Goal is to create a sync each day from hdd_master to backup1 and a backup from backup1 to backup2.
I don't want the snapshots for backup2 on hdd_master but on backup1 because I have no many space on master. The external backup2 will be connected just some times. Possible just one time by year. So the snapshots used for backup2 can have many old files today deleted.

If it's no possible, I will create a script for that but I prefer just use this tool :) with your configs files system.

Thanks.