There isn't currently a Parental Salutation wildcard/merge field in Schoolcomms. However if you manually type: $ParentalSalutation$ this should enter the parents name. You may want to test this first to ensure it works correctly but this should insert parents names.
If you are using the manually typed $ParentalSalutation$, it will pick up the Parental Salutation from the respective field within Section 5 of the child's SIMS record.