how to combine audiobook chapters in itunes

Hi guys,

Hope all is well. Can anyone assist in trying to combine audiobook chapters in iTunes so they show up as one file on my iPhone, with multiple chapters. Hope that makes sense?!? sorry.

e.g. Some audiobooks are multiple chapters on my iTunes, which then show up as one file file on my iPhone with multiple chapters within. Others sync as the chapters themselves.

Best wishes,

Mani