I would like to create database replication between multiple localisation. There will be one publisher and multiple subscribers. Is it possible to define that synchronisation is synchronous only for one subscriber and for the other is asynchronous operation. Is it possible to dynamically modify which subscriber will get data synchronously? Are there any external tools allowing to do that?
SQL Server supports Transactional, Snapshot and Merge replication. They are inherently asynchronous.
Mirroring on the other hand does support synchronous/asynchronous commit however you can only mirror one database to one other location.
SQL Server doesn't support what you are looking for. I'm not aware of any other tools which would enable this either.
The closest thing to what you are talking about is AlwaysOn, which I believe in SQL Server 2014/2016 supports multiple asynchronous/synchronous replicas.