Hi,
Thanks for your question on the Composite module in Web 3DNA 2.0. Composite is an advanced feature that mades use various 3DNA programs and ad hoc scripts. Other than the general idea, I honestly do not know how things work in details. Right now, I have no time to dig things up either. In the long run, I may consider to consolidate all these steps into a DSSR module to automate the process.
Shuxiang, the developer of Web 3DNA 2.0 but no longer involved in the project, may chime in with some insights.
Xiang-Jun