Build link between cad and part in Windchill through code

I have loaded the cad file first in Windchill and the associated part later.So cad part and the part do not have link.

I need to create the link for each epm document.This can be done manually using "Edit Association" for each EPM Document by opening in Windchill .

I need this to be done through java code.

Anyone can give a method how to build the link through code?

Thanks.