Path To Selection

[Krikor]

Hello,

1- Initially I trace some strokes on separate layers.
2- Then I merge these paths in a single layer, but the result that is obtained from the selection of this path does not match the created paths.
3- I would like to be able to get a selection close to what you can see in the illustration below this image (3):



Is there any way to achieve this with Gimp? 

I've tried the Join Strokes plugin but no success.

Thx!