Observers are objects inside or outside a concurrent object system carrying checking conditions about objects in the system (possibly including itself). In a companion paper \cite{EP00}, we show how to split and localise checking conditions over the objects involved so that the local conditions can be checked separately, for instance using model checking. As a byproduct of this translation, the necessary communication requirements are generated, taking the form of RPC-like action calls (like in a CORBA environment) among newly introduced communication symbols. In this paper, we give an algorithmic method that matches these communication requirements with the communication pattern created during system specification and development. As a result, correctness of the latter can be proved. In case of failure, the algorithm gives warnings helping to correct the communication specification.