When you get an issue that was caused by the child having more than one contact marked as Send Letter for the round, see the information below.
Within the Synergy Client, open Admissions.
Press OK within the child query and open the child record.
Within the Contacts tab, open each contact record and review the Round Letters tab.
Untick the Send Letter checkbox for the round for the non-main parent contact.
The result will be to have only one contact with the Send Letter tick for the round in question.
You can identify all children who are affected by this issue by performing the following child query:
On the Admissions tab, select the round within the Round dropdown.
Select the Contacts tab and tick the Multiple Contacts exist with the Send Admissions Letter option ON.
Click OK.