Recursive Petri Nets (RPN) are used to model systems composed of dynamic threads. In this paper, the proposed extensions improve the communications via global places and immediate transitions. For this new model called ERPN, we address the reachability problem in a modular approach. Because threads are dynamic, their abstractions requires to preserve traces of the ability to communicate. For the concern of infinite ERPNs, semantical constraints are proposed to ensure the termination of the reachability procedure.