[Elenna]

Kursed,

Yes, there is an option to have it reply to an existing thread.

Search for this text:

////////////////////////////////////////////////////////////////////////////////////////////////////
//CHOOSE WHETHER YOU WANT FORM TO BE POSTED IN A NEW THREAD, NEW POLL, REPLY TO EXISITING THREAD, PMed OR EMAILED
///////////////////////////////////////////////////////////////////////////////////////////////////

A few lines under it, you'll see the following option:

////////////////////////////////////////////////////////////////////////////////////////////////////
//ENABLE FORM TO REPLY TO EXISTING THREAD - 1 = yes, 0 = no
$formreply = "0";
//EXISTING THREAD ID FOR FORM TO REPLY IN
$formreplythreadid = "12345";
////////////////////////////////////////////////////////////////////////////////////////////////////

Set $formreply to 1, and set the $formreplythreadid to the thread ID of the thread you want the replies to continue to be posted to.

Note: You probably want to look just under the first text and turn off posting new thead, as I believe it might do both if you don't!