Replication failover

Hi guys,

I am looking for a solution to a problem i am having with a pair of
databases we have.

I am looking to migrate my databases from one set of hardware to another
all the servers are running PGSQL 9.x

At the moment we have a primary server replicating to a secondary server
via the streaming method (server1 and server2). If the primary every
fails we can use the trigger file on the secondary to bring the database
back up and running.

Though i am going through a process of upgrade all the database hardware.

I have another pair of databases ready to take over(server3 and server4).

I want to be able to add server3 as a warm standby to server1, then have
server4 as a hot standby for server3. Then fail over to server3 and have
the new database in production.

The problem i have is that when i fail over to server3 using the trigger
file it will increment the timeline which will stop the replication of
server4.

The work around i am using at the moment is to put server3 into base
backup mode and rsync the data to server4 which can take a few hours.

Is there an easier way to do this? Or a way for server4 to recognise the
timeline change on server3?

Thanks

TJ