  Changes in the number of Weyl nodes in Weyl semimetals occur through merging
processes, usually involving a pair of oppositely charged nodes. More
complicated processes involving multiple Weyl nodes are also possible, but they
typically require fine tuning and are thus less stable. In this work, we study
how symmetries affect the allowed merging processes and their stability,
focusing on the combination of a two-fold rotation and time-reversal
($C_2\mathcal{T}$) symmetry. We find that, counter-intuitively, processes
involving a merging of three nodes are more generic than processes involving
only two nodes. Our work suggests that multi-Weyl-merging may be observed in a
large variety of quantum materials, and we discuss SrSi$_2$ and bilayer
graphene as potential candidates
