  The physical link of the star formation-AGN activities is analyzed from
multiwavelength energy distributions of distant radiogalaxies (RG) with the
help of two models: the new evolutionary code PEGASE.3 with dust predictions
and the Siebenmorgen's AGN model, with the aim to to disentangle the farIR dust
emissions from respectively interstellar medium and torus of RGs. Best-fits of
the HST-Spitzer-Herschel (UV-to-IR) observations of the 3CR RGs with libraries
of hybrid SED templates identify three components (AGN, old galaxy and young
starburst) tracing the relation of starburst-AGN luminosities. To confirm this
relation at higher resolutions, the JWST/NIRCam, MIRI and NIRspec instruments
are needed, SED libraries and evolving colors of galaxy hosts adapted to the
JWST instruments are in preparation with PEGASE.3.
