We'll consider how to simplify this, but the current method for merging multiple text items seemed fairly efficient to us:
http://www.kinook.com/UR/Manual/combineinfoitems.htm
If your goal is to combine multiple web pages into a single RTF document, instead of pasting each page into the tree to create separate web page items, you could either
a) paste each page into the details of a single text item (after copying a selection or a Select All of the entire page from the browser)
b) Edit | Paste Special | Rich Text, then combine the created text items