Heusler metamagnetic shape memory alloys have attracted much attention since the discovery of magnetic field-induced reverse martensitic transformation in Ni-Mn-In. On cooling, these alloys undergo martensitic transformation (MT) from the ferromagnetic austenite to a low magnetization martensite, accompanied by a large magnetization drop. The occurrence of such magnetostructural transition opens the possibility for magnetic shape memory effect and other properties. For the Ni-Mn-Ga alloys, both phases display ferromagnetic properties preventing the occurrence of magnetic field induced MTs. However, Co addition not only increases the ferromagnetic coupling of austenite but also weakens the magnetic interactions of martensite, thus a metamagnetic martensitic transition may occur. The type of magnetic order of martensite sets the magnetization jump across the MT, hence its knowledge is critical to approach the best conditions for magnetic field induced MT.We propose a comparative study between a Ni-Mn-Ga alloy and a set of quaternary compositions with increasing Co substitution of Ni to achieve a better understanding of the metamagnetic behavior of Ni-Co-Mn-Ga system.