Transform Map not showing Target table I want

[Mitchell Moses]

I am trying to mass subscribe 400+ user to a communities forum by taking excel file in with their names and then (through script i guess) add them to the forum in the sn_actsub_subobject_stream table, but I can't use the sn_actsub_subobject_stream as a target table. So how am I supposed to subscribe these people to this forum without having to do a ton of approvals, etc. I was just hoping to write a transform to make it easy. 

[Mitchell Moses]

When I am importing records to a table and just pulling the user's name. What script should I use becuase I will be pulling just the name and then I will need to fill out the rest of Target's table info.