By polarized neutron reflectometry we want to investigate the magnetic field profile in Y(1-x)PrxBa2Cu3O7/La(2/3)Ca(1/3)MnO3 high-Tc superconductor/ferromagnet superlattices. In particular, we will focus on the anomalous superconductivity induced changes of the ferromangetic state. Previously, a drastic decrease of the ferromagnetic domain size for superlattices with optimally doped YBa2Cu3O7 and a large modulation of the ferromagnetic order along the direction vertical to the layers for strongly underdoped Y(0.6)Pr(0.4)Ba2Cu3O7 has been observed. These intriguing phenomena which highlight an unusually strong mutual interaction between the superconducting and ferromagnetic orders will be further explored by varying parameters like the doping state of the YBa2Cu3O7 layers and by using different substrates which do not share the complex structural behavior of the previous SrTiO3 substrates