I've got a part that is going to grow and shrink based upon a global variable at the assembly level. Above a certain length, I want that part to suppress and unsuppress two features.

The idea is that when I only need a single cut out in my part, it places my block in the midpoint of the edge. When it grows and I need two cut outs, there is supposed to be three lines with an equal length relation that will automatically space the cuts along the edge. 

What I'm seeing is that once I grow above my threshold, I have to rebuild a few times and / or edit the sketch containing the blocks. Any idea why? I've attached the part and block below. For reference, the part is currently growing from a dimension in Sketch 1 due to the lack of the assembly to control it.