Replication system only works Server → client. So your ball cannot use replication. You have to do it all manually.
On change RPC the new values to the server proxy. Have the server proxy update its transform (snap), then multicast that value to other clients (sims). Have the Sim proxy update the ball.
For this to be smooth you’ll need to write a buffer and interpolate update to update on sims.
A → B…set new A.
A → B…set new A.
A → B…set new A.