i don't think that there is a way to merge sites.
Also could you please be more specfic.
But the objective can be achieved with REPLICATION.
Replication may be defined as the duplication of data on more than one system. The process of duplicating the data records from one database to one or more other databases occurs in near-real time, and is known as replication.
Note "Multiple SEPMs connected to the same database constitutes data sharing, not replication"
Replication Partner
For example, you may set up one site and your main office (EMEA) then install a second site (NAM) as a replication partner to the first. The databases at the EMEA site and the NAM site will be reconciled using the configured schedule. If a change is made in EMEA, it will appear on the NAM site after replication occurs, followed by the replication of changes made at the NAM site to the EMEA site. Later, you can install a third site (APAC) which replicates with EMEA or NAM and which is a replication partner to both sites.
Replication does not occur directly between databases
, rather the merge data is provided to replication partners via the same SEPM servlets that provide communication to the console application. Although it is most common that all sites would have the same type of database, replication can be set up between SEPMs using different database types. For example you can set up A replication partner is another site with one or more SEPMs which has an association to the local site. A site may have as many replication partners as needed. All replication partners share a common certificate. The changes made on any replication partner are replicated to all other replication partners during database replication.
Replication