ADFS 3.0 How to Add an Account Partner?
Solution 1:
Which ADFS do you want to be the IDP?
That ADFS needs to be the Claims Provider, The other is the Relying Party.
Get each ADFS's metadata:
https://myADFS/FederationMetadata/2007-06/FederationMetadata.xml
and import when you are creating the CP / RP.
If you want either to be the IDP from both sides then you need to configure two relationships:
A as CP - B as RP and also
B as CP - A as RP