Requirements prioritisation is a key decision making activity of the software development process, which relies on the capability of different decision-makers to identify the optimal candidate rankings of the requirements, in order to be able to perform a strategic choice among them. In this paper, we formulate such multi-decision-maker requirements prioritisation as a multi-objective optimisation problem, and outline a solution that takes advantage of metaheuristic algorithms. The proposed solution allows different decision-makers to specify their rankings according to a set of prioritisation criteria, it then synthesises them into a set of Pareto optimal global rankings. The ultimate choice of the prioritisation of the requirements would be made upon a focused analysis of the trade-offs amongst the solutions on the Pareto frontier.