You could timestamp the methods sent. From client A to server you send the client A timestamp. From server to client B you send the client A timestamp.
ClientBTimestamp - ClientATimestamp = time passed since clientA started jumping.
If you also pass the client location, rotation, linear velocity and angular velocity as parameters you could simulate the movement since client A started the jump.
I think it’s better to synchronize with what the server has instead of the client, though.
I use std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count(); to get the UTC time between machines. You need to #include <chrono>