By default, dynamic shares will share records for the table you select as well as any associated child table records for that table. However, if you want to dynamic share only the records for the table you have selected in the dynamic share form, you can make use of the Share base table only checkbox under Trigger Conditions.
By checking the Share base table only box, child records associated with your selected table will not be dynamic shared out to your subscribing instances. Only the records for the “base table” (table selected from the Table dropdown in the dynamic share) will be dynamic shared. For more information, see share base table records only.