The migration of legacy web applications (LWA) to Service Oriented Architectures (SOA) has become mainstream in the last years due to the architectural flexibility that SOA provides, which allows to easily adapt the existing applications to new requirements. However, these migrations are usually ad-hoc and manually performed leading to tedious and error-prone processes. MigraSOA is an approach to migrate (and modernize) LWA to SOA that makes use of Model-Driven Development techniques to face the complexity of the underlying technologies, web services, business processes definition or executable business processes platforms. In addition to globally introducing MigraSOA, this paper focuses on the alignment of the business processes defined by the company with the underlying web services of the LWA. Moreover, the paper also shows a process to extend the BPMN models in order to keep these models synchronized with the available services.