A method for designing a 3D modeled object can implement a modeling graph having nodes that represent geometrical objects and arcs that each represent a relationship, wherein procedural relationships are represented by unidirectional arcs, wherein the relationships linking the geometrical objects further include live relationships that are represented by bidirectional arcs, and wherein the provided modeling graph respects a criterion that all the arcs of each strong component of the modeling graph are bidirectional. Upon adding a relationship linking two of the geometrical objects that are included in the data defining the 3D modeled object before the addition, the method selects two geometrical objects to be linked by the relationship to be added, the selection being performed according to the criterion.