How would you combine these sumps?

[Baffels]

Looking to combine these sumps to make a... super sump. Adding another tank into the system. Currently running a reefmat 1200, skimmer and fuge in the redsea sump.

How would you combine these? Where would you put... stuff? Looking to do 2 separate return pumps.

Looked into just getting a bigger sump, but can't find anything shy of 1k.

 

[blaxsun]

Without knowing the size of the second tank it's hard to guess. Assuming the first tank is a 625?