We have investigated the magnetic and magnetoresistance (MR) properties of [Py/Cu 9Å] 2 0 , by addition of thin Co and Fe interface layers, and by varying the thicknesses of Py from 10 to 80Å. The temperature dependence of MR and resistivity from 4.2 to 300K has been analyzed using a semiclassical theoretical model. The increase of giant magnetoresistance amplitudes for [Co 3Å/Py/Co 3Å/Cu 9Å] 2 0 has been interpreted in terms of a reinforcement of the magnetic ordering of the Py/Co/Cu interfaces. It also has been attributed to a more selective transmission of the spin-down through the interfaces of Py/Co and Co/Cu, compared to the one through the Py/Cu interface. Nevertheless, with the addition of 3Å of Fe at the interfaces Py/Cu, one observes a strong reduction of the magnetoresistance amplitudes.