Adding SubForm rows via script

I am having a hard time figuring out if this is possible or not to add rows to a subform through script. What I want to be able to do is have a stateless form where I indicate the record to be updated and the record to be updated from. It works fine for all of the info I want to duplicate expect for the subform data. The subform are bidirectionally linked to the main forms, but I can't figure out a way to add them to the record getting the duped data. I would love some help.

Gabe