  Inspired by the recent precise data, we perform model-independently an
isospin decomposition of the timelike octet baryons electromagnetic form
factors. As noted in our previous work, the relative magnitude of isoscalar and
isovector component is determined with the input of data on various isospin
channels. Herein we further assert that {their relative phase can be constraint
by the phase difference of oscillatory modulation of effective form factors}
between isospin channels. The framework is extended to analyze the data of
differential cross sections and applied to the form factors of nucleon and
hyperons with detail and isospin non-conservation of charmonium decay into
baryon-anti-baryon as well. We address that isospin analysis is meaningful when
the isospin broken scale is compared to or smaller than the uncertainties of
data.
