DROP TABLE IF EXISTS t1, child1, child2;
CREATE TABLE t1 (a <INT_COLUMN>) ENGINE=<STORAGE_ENGINE> <CUSTOM_TABLE_OPTIONS> UNION(child1);
SHOW CREATE TABLE t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `a` int(11) DEFAULT NULL
) ENGINE=<STORAGE_ENGINE> DEFAULT CHARSET=latin1 UNION=(`child1`)
ALTER TABLE t1 UNION = (child1,child2);
SHOW CREATE TABLE t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `a` int(11) DEFAULT NULL
) ENGINE=<STORAGE_ENGINE> DEFAULT CHARSET=latin1 UNION=(`child1`,`child2`)
DROP TABLE t1, child1, child2;