1. How close is the position of the barycentre to an arithmetic sum of each individual planetary influence?
2. How close an approximation of the barycentre plot will be obtained by calculating the pull of each individual planet on the position of the sun and graphing the combined result?
3. Is combined planetary gravity significant in addition to individual planetary effects?

Wiki page here shows tabular calculations and diagrams for two-body barycentres, but in the actual solar system the barycentre moves in response to gravity of all the planets.

Very grateful for any answers
Thanks