Making an exception by parametric facade (blinds)

Greetings! First to say that I am preety much newbie. I am attempting do create blinds for the building I am currently drawing as an assigment on my university. I moved the middle point on the bottom edge of surface and than lofted it with a upper one. After that I have applied the same script once again to make blinds look more playfull. However, I would like to keep the bottom edge simple as it was in the first picture and to leave other parts as they are. Because I have to draft all the time it is hard for me to select needed parts exclude them before I can replace them with one simpler line that I could eventualy replace with bottom edge from the first loft.

Thank you in advance