i am new here so sorry if i did something unlogic in my sketch

heres a sketch of a part (photo included but suppressed)

now i have few 3D sketches

what i want to do is

1. join the blue and black sketch into 1 sketch

2. make the new joined sketch have the same curvature of the yellow sketch

3. loft the red sketch to the new surface which is yellow black and blue sketchs ( and part of the gray one)

guide lines are the 2 side gray lines.

can anyone please explain how can this be done ?

thank for your time and help