Asustor AS6210T- two RAIDs or RAID&JBOD

If I add 4 drives (250gb each) and create a raid, can I add additional disks (4tb) that I can access as JBOD?
If so, can I then add 3 more 4tb disks and eventually migrate jbod to RAID? (I am interested in long term expansion as needed).
If so, can I then add 3 more 4tb disks and eventually migrate jbod to RAID? (I am interested in long term expansion as needed).