Everyone - for anyone wanting to control multiple iOS synth apps from the Seaboard rise or Seaboard Block, I strongly encourage you to look at Keystage in the app store.
There have been a lot of requests for a Dashboard for iOS. I for one would very much welcome that and it is sorely needed, and a bit surprising it does not exist.
There is an app out there that has started called Block Dashboard that will serve the needs of some to allow you to change some of the more common and useful params on the block so that you can switch modes and control more apps correctly on iOS.
But Keystage is much more than that and the author is actually quite fond of his Roli Seaboard as well (I believe he has a block and a Rise).
The app can be setup to control MPE compatible synths, non-MPE compatible synths, mulit-timbral ios Synths and even has ways to deal with iOS synths that don't support a wide pitchbend range - by translating the Seaboard's midi into pitchbend signals that the iOS synth can handle - allowing much more widespread use of iOS synths to be possible.
It does splits, layers and is much like a Mainstage type of a solution for all midi controllers but has tons of specialized capabilities for MPE - with a focus on Seaboard.
The video below explains the MPE specific treatments and the other tutorials will get you started:
MPE Keystage tutorial
I encourage you to check it out