UnionSubQuery usq = queryBuilder1.ActiveSubQuery.ActiveUnionSubquery;

    // get WHERE conditions from the usq.QueryColumnList
    using (SQLExpressionItem whereCondition =
        usq.QueryColumnList.GetConditionTree(new[] {ConditionType.Where}))
    {
        // append WHERE links (if any)
        usq.FromClause.AddWhereJoinConditions(whereCondition);

        // format using custom formatter
        using (SQLBuilder sqlBuilder = new SQLBuilderPiped(null))
        {
            // customize sqlBuilder
            sqlBuilder.ParenthesizeANDGroups = true;
            sqlBuilder.MainQueryFormat.WhereFormat.NewLineAfter = SQLBuilderConditionFormatNL.TopmostLogical;

            // build condition using sqlBuilder format settings
            sqlBuilder.BeginBuild();
            try
            {
                whereCondition.BuildSQLCosmetic(sqlBuilder, sqlBuilder.MainQueryFormat, sqlBuilder.MainQueryFormat.WhereFormat, 0, false);
            }
            finally
            {
                sqlBuilder.EndBuild();
            }

            // get result
            string whereString = sqlBuilder.Result;
            MessageBox.Show(whereString);
        }
    }