Breath of Fury attached to another creature you control.
Giant Inheritance attached to any creature except the creature with Breath of Fury attached.
An opponent cannot block creatures you control.
The creatures with Breath of Fury and Giant Inheritance attached do not have summoning sickness.
Steps
Declare the creature with Breath of Fury attached and the creature with Giant Inheritance attached as attackers.
The creature with Giant Inheritance attached triggers, creating a 2/2 Cat creature token with haste due to Jinnie Fay.
Deal combat damage using the creature that has Breath of Fury attached.
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Cat token, then causing you to untap all creatures you control and to get an additional combat phase after this one.