How to find last Pgf of pasted paragraphs?

I'm pasting several Pgf objects at once into a file (a changes file of sections containing changebars), in the main text flow. I want a divider line to go at the end of each pasted section, so I try to insert one after the paste operation. But instead of a line between each section, all lines are added at the end of the file, after all the sections. So if there are 3 pasted sections, at the end of the file are three lines. My code is below, do you know how I might remedy this?

Thanks, Mark

function copyPasteChanges(doc, chgRange) {

    // Select section with changebar and copy it.

    doc.TextSelection = chgRange;

    doc.Copy();

    // Get the changes doc ready and paste the changed section into it.

    var firstChgPgf = changesDoc.MainFlowInDoc.FirstTextFrameInFlow.LastPgf;

    var changesTloc = new TextLoc(firstChgPgf, Constants.FV_OBJ_END_OFFSET);

    var changesTRange = new TextRange(changesTloc, changesTloc);

    changesDoc.TextSelection = changesTRange;

    changesDoc.Paste();

    // Get to end of file again (I think)

    var lastPgf = changesDoc.MainFlowInDoc.FirstTextFrameInFlow.LastPgf;

    var dividerPgf = changesDoc.NewSeriesPgf ( lastPgf );

    var TLoc = new TextLoc ( dividerPgf, 0 );

    changesDoc.AddText ( TLoc, "_______________________" );

}