The McGregor family were friends with the Karauria family & both spouses were pregnant at the same time. As the Karauria family only had daughters & no males to continue the family name, Walter & Tupuae conspired to swap children should the Karauria's not conceive a boy - neither wife new of this arrangement.

The McGregor family already had sons & daughters & figured this would be ok. 

When the time came to give birth the Karauria family delivered another baby girl & the McGregors a baby boy.  True to his word, the families swapped children to the dismay of the wives.  The rest is history..... 

 The Karauria's named their son Tupuae Malcolm after Tupuae Senior