Dynamic block stretching polygon and a circle simultaneously

Please advise me on how to accomplish this action. See picture. Dwg Attached. As I'm stretching the polygone i want the original cirlce to take a shape of red

circle.Thanks

Drawing2.dwg

I'm not at my CAD machine until Tuesday but I think I would look into using constraints (I am sure 2013 has them). I would constrain the circle to the mid point of the rectangle and constrain its diameter to the rectangle's width.

thanks for the quick response,

to set each of the constraints below requires one command or i need to do preparatory work...Book me on tuesday but i'm impatient:(

thanks again

constrain the circle to the mid pointrectangle and

constrain its diameter to the rectangle's width

you need to look in to geometric constrains. I think that is on a tab in the bedit palette.

dbroada here are the constraints, can you break it down for me please

i looked at every parameter no success