Originally, I posted this as plugin, but reconsidered, and think this could be a feature.
It would be cool to be able to quickly combine the content of multiple links (if in editor) or nodes (if in graph view), or even notes (if in file explorer) into a new note. Perhaps, there could be a setting for the max number of lines to include.
I could see some advanced features allowing for adjusting the hierarchy of the composite with relative ease in the process, potentially allowing a commit that would actually link those notes to each other based on that hierarchy, although that would be a bonus feature, yet very powerful. Additionally, by selecting multiple notes in explorer and clicking a create button, it could interpret already existing hierarchy into the composite note for those source notes.
In real time, it could order the source content based on sequence of clicks, and neatly format the new composite note with headers, with undo capabilities. Also, there could be a toggle for whether you want the new note to be linked to or from the source notes, if at all.