I my opinion you are better of using SMO in that case, you somehow save the last
date/time of the entries transfered or another field that help for the next time that the manager click on the transfer button. Here is a start on the smo API http://blogs.msdn.com/b/olivier_pieri/archive/2004/12/06/275825.aspx
the sample show just how to connect to SQL, then go from there accessing the tables from the registration db and write the data on the main db.
You can read more or get more SMO samples from Microsoft.