How to mate parts between sub-assemblies

Hi All,

I am self taught at SW so this would probably be an easy one for someone.

I am doing a structural steel job.

I have set out a few beams and have drawn a plate in one of the sub assemblies.

I now want to use the same cleat in a different sub assembly but cannot mate it to where i want.

Could some one please help me out?

I have attached a screen shot and the file if anyone could try to help me.

Thanks!

SolidworksAssemblies