Ferroelectric and ferromagnetic orders rarely coexist, and magnetoelectric coupling is even more scarce. A possible avenue for combining these orders is by interface design, where orders formed at the constituent materials can overlap and interact. Using a combination of magnetotransport and scanning superconducting quantum interference device measurements, we explore the interactions between ferroelectricity, magnetism, and the two-dimensional electron system (2DES) formed at the novel LaAlO3/EuTiO3/Sr0.99Ca0.01TiO3(001) heterostructure. We find that the electrons at the interface experience magnetic scattering appearing along with a diverging Curie-Weiss-type behavior in the EuTiO3 layer. The 2DES is also affected by the switchable ferroelectric polarization at the Sr0.99Ca0.01TiO3 bulk. While the 2DES interacts with both magnetism and ferroelectricity, we show that the presence of the conducting electrons has no effect on magnetization in the EuTiO3 layer. Our results provide a first step towards realizing a new multiferroic system where magnetism and ferroelectricity can interact via an intermediate conducting layer.