Multiple Instance mode acting oddly

[Andrew Ducker]

My desired functionality would be as follows:
When I first launch Notepad++ it would load all of the files I last had open.
Further command-line launches would either launch in that window (if launched with just the filename of the text file) or in a wholly separate window, depending on whether I launch with -multiInst.
Instead, what happens is that launching with -multiInst causes a new window to spawn complete with all of the previously-opened files, so I end up with multiple copies of the files open in different windows.

I guess that what I’m looking for here is a way of simulating an MDI interface - each file open only once, with most of them in tabs, and the odd one appearing in different windows.

Is this something that’s feasible?