Your existing setup is a FAS2240-4 and a DS2246 (not a 2240-2 - that is a controller.. which is what the picture 2 shows).
The system in picture 2 can be converted into another DS2246, by replacing the FAS2240 controllers with IOM6 modules (only - IOM3 is not supported). All you need is the two IOM6 modules and sufficient SAS cables. Be aware that the FAS2240-2 may have partitioned disks, so you probably want to boot it, unpartition them if partitioned, then convert it into a shelf by replacing the controllers with the IOM6s.
SAS cables plug circle to square, start and finish the chain in different controllers