It looks like one just needs to expire a data dam to pass data through it (i.e. simply recomputing a definition will also work). Here’s a quick GhPython script that appears to work as expected. I usually target specific components on canvas via their NickName when using this coding pattern (i.e. iterating all components on canvas by type, followed by nick name). But it doesn’t seem possible to edit this directly on data dams, so here I’m targeting by names of the first input parameter instead:
240829_TransferDataDams_02.gh (9.7 KB)
Edit: Removed previous post/definitions for clarity.