How put lines to the inset

Dear all,
I am trying to get an image that extracts an inset and that have some lines to the inset. to show which part of the original map is in the inset. Any smart suggestions on how can I do this?

so far I have introduced two insets in the image one that is outside the Map and one with no colour background and with the same coordinates but I hope there is a better way to do this and to actually plot the lines to the inset.
I would appreciate any good help !