sql server replication: I need to replicate data between two servers through modem. The
problem is that the modem always disconnect in the middle of the
process.
This is not the initial replication. There were some success until the
last days, and there are data changes in both publisher and subscriber
that need to be merged.
Is it possible to transfer the merge data manually?

You can't do this manually. You could change the merge agent properties to
optimize for an unreliable link - eg reduce the '...GenerationsPerBatch'
counters, and force it to restart after a network failure (3rd step -> 1st
step).
Rgds,
Paul Ibison SQL Server MVP, www.replicationanswers.com
(recommended sql server 2000 replication book:
http://www.nwsu.com/0974973602p.html)