Hello Paul,
This has been asked quite a few times before, but currently it is not possible to open multiple custom bars at the same side. However, you can change where you want to open a custom bar for each plug-in, and so you can adjust the custom bar layout. I have been thinking about adding the ability to pin or cascade multiple custom bars, but I didn’t want to make EmEditor too bloated, and I rather want to focus on improving the core features of EmEditor.
Thanks!