Currently the fastest way to insert a Bundle By Name node into an existing cluster wire is to use the QuickDrop Ctrl + I shortcut.
Holding down a modifier key (Ctrl, Alt, Shift, or a combination of these) while double-clicking on an existing cluster wire would be even quicker.

Notes
- Inserting BBN nodes is a common, repetitive action when working with clusters. For example, when working inside the Message Handling Loop of a DQMH module.
- The gesture should work for class wires too, but only if access scope rules allow it.
- This idea is very much related to the "New gesture to create Unbundle By Name node (Ctrl + double-click when creating a cluster wire branch...". The difference is that this idea addresses inserting BBN nodes into existing wires. That idea addresses more easily terminating a new wire branch with a UBN or BBN node.
Thanks