Styriam Shaped Curves Merger

This add-on is meant for joining curves with shape keys. Normally, curves can be joined with Ctrl+J shortcut but using this on curves with shape keys leads to a loss of animation data. Fortunately, this add-on can merge curves and copy shape keys along with their f-curves and their modifiers.

Select curves in object mode and find Join Curves in the Object menu or in the context menu (right click). The active object becomes a base object for the merge and retains its modifiers and constraints.

In the add-on preferences, you can find an option to hijack the Join shortcut. When enabled, curves with shape keys will be merged by the add-on using the Join's shortcut (Ctrl+J by default).

Workflow advantage

When creating complex motions driven by curves animated with motion keys, you get ability to comfortably divide your work into smaller segments that can be easily joined later. An example of this you can seen in the following video created with Styriam Waveform add-on.