Ferroelectric and ferromagnetic orders rarely coexist, and magnetoelectric coupling is even more scarce. A possible avenue for combining these orders is interface design, where orders formed at the constituent materials can overlap and interact. Using a combination of magneto-transport and scanning SQUID measurements, we explore the interactions between ferroelectricity, magnetism, and the 2D electron system (2DES) formed at the novel LaAlO₃/EuTiO₃/Sr_0.99Ca_0.01TiO₃ (LAO/ETO/CSTO) heterostructure. We find that the electrons at the interface experience magnetic scattering appearing concomitantly with a diverging Curie-Weiss-type behaviour in the ETO layer. The 2DES is also affected by the switchable ferroelectric polarization at the CSTO 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 ETO layer. Our results provide a first step towards realizing a new multiferroic system where magnetism and ferroelectricity can interact via an intermediate conducting layer.