Sketch of the evolution of the feedback-driven shell around Cluster 1 in W49A (see text for details). At t = 0, Cluster 1 (red) is formed in the models (left panel). The feedback from Cluster 1 drives a shell into the molecular gas of W49A (middle panel). The radii of maximum extension from Fig. 6 are highlighted (Model 1, 2, 3 in red, yellow and blue, respectively). The shell then re-collapses to its observed extent (right panel). The other stellar sub-clusters, as well as the Welch-Ring, are highlighted in blue in the right panel to indicate their relative position. In the left and middle panels, these objects are highlighted in gray to indicate that, depending on the model, they may not have formedyet and that their formation may have been triggered by the feedback-driven shell around Cluster 1. The stellar clusters/Welch ring are not to scale.