You can easily setup replication from and to remote instances doing:
POST /_replicate HTTP/1.1
{"source":"http://example.org/example-database","target":"http://admin:password@127.0.0.1:5984/example-database"}
I am not sure if it will split the replication if you have both going at the same time. I am guessing it will just try to replicate all documents twice, getting a conflict the second time it attempts it.
I am not familiar with that DB, but what you can do to split the replication is let each instance replicate certain databases within isaacs. That will split the replication for you since each database will only get replicated once. If there is only one database, that isn't very helpful then.