In Lévy processes, the Wiener-Hopf factorisation describes the way the sample path achieves new maxima and minima in terms of a pair of subordinators. Vigon’s theorem of friends is its converse: a way to construct a Lévy process with known Wiener-Hopf factorisation out of a given pair of subordinators which are 'friends'. In this talk, I will discuss the analogous problem for Markov additive processes. I will give some sufficient conditions for friendship of Markov additive subordinators, and show that some new subtleties arise. This is joint work with Leif Döring (Mannheim) and Lukas Trottner (Aarhus).