Custom Extension
<Biml xmlns="http://schemas.varigence.com/biml.xsd">
<Tables>
<!-- Custom Extensions are custom SSIS tasks which can run after table creation -->
<Table Name="SampleChild" ConnectionName="TableConnection">
<Columns>
<Column Name="Column1" DataType="Int32"/>
</Columns>
<CustomExtensions>
<CustomExtension Name="CustomExtension" ConstraintMode="Linear">
<Tasks>
<ExecuteSQL Name="SimpleTask" ConnectionName="TableConnection">
<DirectInput>
ALTER TABLE SampleChild ADD Column2 BIGINT NULL
</DirectInput>
</ExecuteSQL>
</Tasks>
</CustomExtension>
</CustomExtensions>
</Table>
</Tables>
</Biml>