I set up P2P replication using SQL Server 2014 Enterprise (ServerA) at one end and SQL Server 2012 Enterprise (ServerB) at the other end and did some insertions at both ends and the new rows got copied from A to B but not from B to A. ServerA has the higher originator ID. I'm new to P2P so it's possible I'm missing something obvious.
Doh! There was an error that I didn't notice in the replication monitor, apparently I hadn't given the service account of ServerB access to ServerA. Once I did that the rows showed up in ServerA. Now if I could just find some instructions on how to set up the identity ranges for specific servers...