Constraining the behaviour of the young massive stars through interferometry

The formation of multiples has seen some significant progress over the past years mainly due to the advent and the expansion of high-angular resolution facilities. Star-forming regions are the laboratories where massive stars can be caught right after their formation phase. Still, the observational constraints and the properties of young multiple systems are poorly documented. These proceedings contain recent results about the multiplicity properties of six young O-type stars in the M17 star-forming region, observed by the means of near-IR interferometric observations, which have provided insight into the origin of massive close binaries in a cluster environment.