When there are insufficient inputs for a product-level approach to requirements elicitation, a process-level perspective is an alternative way for achieving the intended base requirements. We define a V+V process approach that supports the creation of the intended requirements, beginning in a process level perspective and evolving to a product-level perspective trough successive models derivation with the purpose of creating context for the implementation teams. The requirements are expressed through models, namely logical architectural models and stereotyped sequence diagrams. Those models alongside with the entire approach are validated using the architecture validation method ARID.