Thanks for the quick reply – it works!
As I understand it (digging into the code), all default layouts in /wp-content/plugins/magic-post-listing/app/widgets/MPL may be overridden by files in /wp-content/themes/mytheme/webilia/magic-post-listing/app/widgets/MPL, but no new layout may be added this way.
Therefore I replaced the “default” layout with mine and I’m all set.
Thanks again,
Alyaron
