Model-driven engineering can help in mitigating ever-growing complexity of modern software systems. In this sense, the Unified Modelling Language (UML) has gained a thick share in the market of modelling languages adopted in industry. Nevertheless, the generality of UML can make it hard to build complete code generators, simulators, model-based analysis or testing tools without setting variability in the semantics of the language. To tailor semantics variability the notion of semantic variation point has been introduced in UML 2.0. Our research focuses on the semantic variation point that leaves the rules for matching multiplicities of connected instances of components and ports undecided in UML composite structures. In order to allow model analysability, simulation and code generation, this semantics needs to be set. At the same time, leaving the burden of this task to the developers is often overwhelming for complex systems. In this paper we provide a solution for supporting modelling and automatic calculation and generation of explicit interconnections in complex UML composite structures. This is achieved by (i) defining a set of connection patterns, in terms of a UML profile, and related semantic rules for driving the calculation, (ii) providing a generation algorithm to calculate the explicit interconnections.