Thanks Matt!
Yes you can create an aggregate for the 24 and 16 and although a bit unstable in Pro Tools, it’s a train wreck in Studio One. There are also some “gotcha’s” when it comes to elegantly linking audio. Sub out of the 16 into two channels of the 24 works but the 16 won’t feed FX’s or Monitor 1 and or 2 out the sub into the 24 which leaves the FX processor useless.
By and large I’m working on it and from a seamless solution I might use the 24 as my main mixer and interface and the 16 as a sub-mixer for my synths.