the answer is in: protected $connection = 'mysql';
set two connections up and then reference each in their appropriate model.
'connections' => [ // First Database 'database1' => [ 'driver' => ...... ], // Second Database 'database2' => [ .....
Then in each model set the correct connection (database):
protected $connection = 'database1';
I have implemented this successfully, but caution that the whereHas does not seem to be working across databases