Adding up numbers and showing them with connecting lines

Hello,

I have a question about adding up numbers and showing them with connecting lines. I have a structure where the left bottom and top are equal to a normal force of zero. Now I want to add up several numbers to this. 

The numbers I want to add up can differ from each structure (depending on intersections with vertical elements). In this example I want to add up 3 numbers to the lower horizontal element en 3 numbers to the upper horizontal element (see images). Now I want at each intersection the value and a line drawn between (see image).

The lower element runs than:

0.0 -> -131.6 (at 1st intersection) -> -131.6 (at 2nd intersection) -> 0.0 (right bottom intersection)

The upper element:

0.0 -> +131.6 (at 1st intersection) -> +131.6 (at 2nd intersection) -> 0.0 (right bottom intersection)

So basically I want to add up the first 3 variables to the first value in list;Normal force begin

and add up the last 3 numbers to the second value in list;Normal force

Hope somebody has an answer