i understand that there are 2 main ways to observe and determine properties of exoplanets but my question relates to the method which involves measuring the "wobble" caused by the gravitational influence of a planet on it's parent star. is the measurement always based on the assumption that only one planet is present in the solar system in question and would the presence of other, as yet unobserved planets affect conclusions drawn about the mass and orbital distance of the planet. would the presence of other orbiting planets cancel out the "wobble" or accentuate it?