Allow directional splits about fm-nvim

[is0n]

I'm afraid this is something that is most likely not possible. fm-nvim opens files by reading /tmp/fm-nvim and this file is only created and written to upon the closing of a file manager.

If you want to open multiple files with a single instance of a file manager, then you can select the files you want to open with your file manager's selection tool.

With Ranger for example, you could just press space while hovering over the files you want to open and there you'll be able to open all of the files with just a single instance of Ranger.