You can convert Cross references in FrameMaker to hyperlinks
in RoboHelp and also append a text in front of these hyperlinks.
Have you used a cross reference format definition which is unique
to Related Topics. If yes, when you map cross-reference formats and
select building blocks in the mapping dialog in RoboHelp, you can
also append a text "Related Topics -" just before the mapping. The
cross reference will appear as "Related Topics -
<$paratext>". If you have multiple cross-references listed
together, you may want this to appear only once for the first
hyperlink and use a comma separator. You can refine this by
creating two cross reference format definitions in FrameMaker, one
for first cross-reference and another for following ones. Small
modifications in this workflow should get the desired
results.