Input DataFrame: rowsCount = 7, columnsCount = 5

name		age	city	weight	isHappy
firstName	lastName
Alice	Cooper	15	London	54	true
Bob	Dylan	45	Dubai	87	true
Charlie	Daniels	20	Moscow	null	false
Charlie	Chaplin	40	Milan	null	true
Bob	Marley	30	Tokyo	68	true
Alice	Wolf	20	null	55	false
Charlie	Byrd	30	Moscow	90	true

Step 1: Merge

name	merged	city	weight
lastName
Cooper	[Alice, 15, true]	London	54
Dylan	[Bob, 45, true]	Dubai	87
Daniels	[Charlie, 20, false]	Moscow	null
Chaplin	[Charlie, 40, true]	Milan	null
Marley	[Bob, 30, true]	Tokyo	68
Wolf	[Alice, 20, false]	null	55
Byrd	[Charlie, 30, true]	Moscow	90

Output DataFrame: rowsCount = 7, columnsCount = 4

name	status	city	weight
lastName
Cooper	Alice aged 15 is happy	London	54
Dylan	Bob aged 45 is happy	Dubai	87
Daniels	Charlie aged 20 is not happy	Moscow	null
Chaplin	Charlie aged 40 is happy	Milan	null
Marley	Bob aged 30 is happy	Tokyo	68
Wolf	Alice aged 20 is not happy	null	55
Byrd	Charlie aged 30 is happy	Moscow	90