adding new app by duplicating DOSBoxPortable with custom autoexec

Hi.

I'm trying to add a new launcher in Portable Apps. What I did is create a copy of the already installed PortableApps\DOSBoxPortable folder.
The new folder name is PortableApps\Lemmings, and inside that new folder I renamed DOSBoxPortable.exe into Lemmings.exe.
Then, I edited PortableApps\Lemmings\Data\settings\dosbox.conf to add :

[autoexec]
# Lines in this section will be run at startup.
mount c \dos_apps
c:
c:\lemmings\vgalemmings

Whenever I executes Lemmings.exe directly from the regular Windows Explorer (double click or right click > Open), it works as expected by starting DOSBox and then executing vgalemmings.exe straight away.

But for some reason it doesn't work when I try to start it from the PortableApps menu. Initially I had a second "DOSBox Portable" entry instead of "Lemmings", and it didn't work (nothing happened when I clicked on it). I renamed the menu entry into Lemmings (right click on menu item > Rename), but it still doesn't work.

Is there a manual way to add a custom App to the PortableApps menu? Any configuration file I could modify to make sure my Lemmings menu entry is actually linked to PortableApps\Lemmings\Lemmings.exe?

I'd appreciate any piece of advice you might have.