Advanced use of multiple instances

[Cyan]

I would like to use multiple instances of VLC, yet still be able open certain media files in an existing instance instead of a new one.

In my case I am using windows 7 64 bit but I am quite sure this also applies to many other OSes.

Example:
I have 2 folders, each containing a couple of mp3 files. I want to open all the mp3 files of the first folder in the same instance. But I want to open all the mp3 files of the second folder in an other instance, having them open at the same time.

So I would like to be able to right click on a folder or file and select which instance(existing playlist) I want to open it with, or if I would like to open it with a new instance.

I also find the current help page insufficient and confusing. There are two options for the use of multiple instances, but there is no explanation offered about the differences between these options.

Can someone tell me how I can achieve the desired result?
If there is currently no solution, can someone give me some advise on a proper solution, maybe I can program it myself, and if it work well, share it with the community.

[Cyan]

Is there really no one but me interested in this feature?
Or is there already a way to do this of which I am not aware?