What is field in Students that has family ID? Show entire query SQL statement. Assuming Family_ID is name of linking fields in both tables and are number type:
SELECT *, ConcatRelated("First_Name", "Students", "Family_ID=" & [Family_ID]) AS Kids FROM Families;
It is possible to do this with a CROSSTAB query. Requires a unique record identifier in Students, an autonumber will serve.
TRANSFORM Max(Students.FirstName) AS MaxOfFN
SELECT Families.FamilyID, Families.FamilyName
FROM Families RIGHT JOIN Students ON Families.Family_ID = Students.Family_ID
GROUP BY Families.Family_ID, Families.FamilyName
PIVOT DCount("*","Students","Family_ID=" & [Family_ID] & " AND ID<" & [ID])+1 IN (1, 2, 3, 4, 5, 6, 7, 8, 9 10);