Just put A and B for the results when initially inserting the
If...then...else field, then after dismissing that dialog, use Alt+F9 to
toggle on the display of field codes and then replace the A or the B as the
case maybe with an {IncludePicture} that points to the drive\\path\\filename
of the scanned image.  Note that the path separators must be doubled.  You
will probably need to update the fields after executing the merge to get the
signature to display.

You cannot do this using the dialog box. You will have to insert the fields
manually using CTRL+F9 for each pair of field boundaries {}

I had a good day yesterday. I started by seeing my solicitor's
father-in-law. He's 86 and very well connected. He handles my insurance and
is a great source of information over a coffee. He introduced me to a
customs clearing agent who will be very useful and advised me on the best
plans for medical insurance and selling the house here. On the basis of what
I learned from the meeting, bringing my car here is a no no. I can keep it
here duty free, but then if I sell it I will then have to pay the import
duty. That could amount to several thousand pounds :( I'll sell it before we
move.

I made an appointment with the aforementioned solicitor who has been out of
the country (in England would you believe) for Thursday and with Theo from
the builders this afternoon. Everything seems to be ticking over nicely.