@gwendol: The song of the heart from the paladin is that 'since you have inspire courage, it should count as you having bardic music for x'. Unfortunately, 'it should' is houserule territory. See the notes under 'Build stub: Paladin 20' and the 3rd level red asterisk and the variants section later in that post. The song of the heart feat requires you to have bardic music specifically.
http://community.wizards.com/content...-topic/3407376
Pretty much acknowledgement from toapat's own super duper source that you pretty much need houseruling to get it to work.