We introduce in (Salaun et al., 2001) the formal foundations to make a generic combination of one process algebra and one algebraic specification language possible. Furthermore, to strengthen the contribution of this work, a concrete illustration about an orders invoicing case study is detailed in (Salaun et al., 2001). In this paper, we especially focus on the addition of other languages; indeed in the initial work, we only consider a restricted number of process algebras: CCS, CSP, ACP, basic LOTOS. Therefore, we aim at formalizing the way to extend the previous combination. To achieve this goal, we present a method to enhance the syntax and semantics of the formal kernel introduced in (Salaun et al., 2001). These guidelines are illustrated with the /spl pi/-calculus.