How would you merge a server? Let’s say guys from other server have their base where your base is on your server?

They need to start opening fresh, new servers, announce it in advance and people are going to queue and wait to join them.
This is how they run things in other games to keep playerbase fresh and engaged.,

Right now Funcom does it wrong.

Right now when you join a PvP server you are against clans that are 6 years worth of building and gathering resources ahead of you - this is madness.
These old servers are dull, rotten and full of stench. They are often filled with bases that are refreshed once every 2 weeks and nobody plays there.

They need to create new rules as to activity, wipe these dead servers and put a fresh ones in their place.

Every other company keeps offering new fresh servers in regular intervals of time.
Funcom needs to learn it too.
I understand costs of adding new servers hence I advise recycling and wiping old servers.