openmediavault-unionfilesystems aufs & snapraid starting with 2 disks

Hello folks,

I want to start my fresh built NAS with a combination of SnapRaid and AUFS but at this moment I only have to disks available.
I already created the parity and data drives for SnapRaid and then recognized that I cannot start a union filesystem because exlcuding the parity disk I just have 1 disk left. I need at least 2 disks to start the union filesystem with AUFS.

So my question is if I skip creating the union filesystem an this moment and start adding data to my data disk, will I be able to create a union filesystem later when I add a second data disk? And will this later creation work without data loss?

I appreciate your help,
thanks in advance

Thanks for your reply.
I followed a tutorial for setting everything up. Maybe it was not that recent because they mentioned AUFS there and so I automatically assumed using it. Thanks for correction