Help with path inside path

[PDR]

Hi there. Ive searched but couldnt found the solution for what i want to do I will explain with images.
I have this situation and what i want to do is fill with black the upper path the red line path but i dont want it to go inside the blue path. Can i full and use the upper line of the blue path as the limit? (second image to explain better)


But i dont want to fill everything inside red path i want something like this:

This is just a scratch to show better what im talkin. Basically I want to fill the red path but not going inside the blue. Because if i fill the red path it will fill all the red including some of the blue path. Is there any way to do what i want to?
Thanks in advance!

[rich2005]

Use the path dock options to create the selection-from-path
First a regular selection from the first path
Then from the second path use the ctrl key to subtract from the first selection.

   

20 second animation https://i.imgur.com/vhd57Zc.mp4