I would use the larger star as root variable for the systems, using the system name as reference to such larger star (therefore, Sol = the sun), then each plane

I would use the larger star as root variable for the systems, using the system name as reference to such larger star (therefore, Sol = the sun), then each planet would adapt their time dilatation from this reference, something like Sol:Earth and Sol:Jupiter, but now I realize even like this the speed of the satellite in origin and destination should also be included, something like Sol:Earth[satellite_speed] and Sol:Jupiter[satellite_speed], but the transit of a satellite between planets would need some kind of progressive sampling witch don't sound specially precise. To me sounds like people specialised tried to design something and got trapped in a loop about witch ideas would be less problematic (what would be interesting to read if my guessing is right). PS: I mean, with something like what I described, we would read the packets at Sun:Earth sent from Sun:Jupiter and from Sun:Mars as time in the header (with the intention of being able also to exclude if they were sent with Radio_wave or Light/laser_wave speeds), the only alternative I can think of is a satellite orbiting the larger star, sending some kind of subspace instantaneous signal from an atomic clock, and read it at each planet instantaneously.