Need to change co ordinate system of assembly & all its sub assemblies to new co ordinate system

Hi all

We have modelled as system with some sub assemblies, But now we need to change the co ordinate system to the assembly and sub assembly offest by some value in X & Z axis.

I have tried to assemble the model with the new co ordinate system & created step file from it. But still the sub assemblies in it are in their old co ordinate system.

Could anyonce please suggest me how to change the default co ordinate system of assemblies & sub assemblies.

Even i am ok with converting it into step & importing it back.

Regards

Udhay