For organisations with the paid destination for Solicitors/Canvassers, this allows you to create a link to the solicitor/canvasser on the gift (see below for where this appears in RE)
Simply select the appropriate solicitor relationship record mapping from the dropdown in the link mapping. You do need to map the Solicitor/Canvasser on the Solicitor/Canvasser tab prior to being able to link that mapping to the Gift.
