Extending an array on an MD3200 + MD1220

Hi there!

I wanted to ask if it's possible to extend an existing array without needing to delete it. For example if we have a MD3200 full with 12x 450GB SAS 15k 3.5" HDDs on a RAID5 array and a MD1220 connected it to it but with just 4x 960GB SSD Drives on a RAID5 array, can we expand this second array by adding extra drives? Or it's necessary to move the data somewhere else and destroy the existing array and rebuild it, instead of just adding more drives on the existing array.

Thanks a lot in advance for your replies.