Custom Lensflare Expression

Hi

i'm creating an own lensfare.I have created all elements and i'm struggling with the position expression of the iris elements.

Can anyone point me in the right direction how to create the following expression=>

Example:When i move the source point of the flare to the right i want certain elements move to the left accordingly,like the build in Lensflare in after effects does.You know what i mean.Well,just pickwhiping and add *-1 doesn't really work. 

any help appreciated