Adding an PDOCG to an existing PDOCMD

Quick question.  How does one add an OCG to an existing OCMD with the Adobe SDK with PDFLib?  Basically, I'm moving an OCG inside another OCG and need to associate them with an already existing OCMD, that I need to update.  I need containers that are set to this OCMD to reflect the visiblity of both of these OCG's, instead of just the previous one.  The Acrobat API says to "To add a group to an existing OCMD, get the current OCG list, modify it, then create a new OCMD with the new list of groups (PD_Layer.PDOCMD (Acrobat)‌."  How does one accomplish that?  I can't quite figure it out.  Thanks for the help!