I've done something like this in XC 4.1.12 to control just one extra field:
Code:
{if $active_modules.Extra_Fields ne ""}
{if $extra_fields[0].field_value eq "y"}
*** Display your html/fields here ***
{/if}
{/if}
HTH
__________________
Developing in 4.7.x now (Dipping into v5 - Slowly!)
Have used 4.1.x, 4.2.x, 4.4.x, 4.5.x, 4.6.x & 4.7.x
Multiple Instances of X-Cart
MySQL 5.6.37
CentOS 7.4
Chamber Internet - Lancashire, United Kingdom
http://www.chamberelancs.co.uk