As the power and utility of virtual reality environments increases, so do the potential benefits found from combining several such environments. But doing so presents the developer with a host of difficult software engineering issues. This paper explores what some of these issues are within the VE domain, relates our successes to date in overcoming these problems by means of various automated tools, and suggests ways to apply our results other target domains. (Also cross-referenced as UMIACS-TR-96-87)