Hi Martin!

Is this part of a drama, or more like prose (I realize that sometimes
Joyce isn't as easily classified as many :-)

Generally speaking, <sp> and <stage> are intended for drama, whereas
<q> is intended for prose. I'm going with the idea that this is
prose. If you like the idea of indicating that "Tell me know" and
"what is a pier" are part of the <soCalled>same</> quotation, then I
would link them in any of a variety of ways:
* next= and prev= from the module on linking, segmentation, and
* <join> elements elsewhere
* add part= to <q> via a customization

Thus, something like

  <p><q xml:id="q017s1" next="#q017s2" who="Stephen">Tell me now,</q>
    <seg type="quoth">Stephen said, poking the boy's shoulder with the
    book,</seg> <q xml:id="q017s2" pref="#q017s1">what is a pier.</q></p>


  <p><q xml:id="q017s1" who="Stephen">Tell me now,</q> Stephen said,
    poking the boy's shoulder with the book, <q xml:id="q017s2">what is
    a pier.</q></p>
  <!-- ... elsewhere ... -->
  <join result="q" scope="root" targets="#q017s1 #q017s2"/>

seems like it would do the trick.