Were it me i wouldn't include any songs with enough old material they require crediting people who've been 15 years dead.

That would not be original by any definition i now.

I disagree, I think 

It's still a mostly original composition produced specifically for the film. will.i.am wrote what he wrote for The Great Gatsby and nothing else, the song is in existence because of the film, and to me, that's enough for a song writer credit.

You have to properly credit anyone who's material you sample for a song. If a song includes one single line specifically taken from another song, the writer of that song has to be credited, it's not a matter of having enough old material to require crediting them, it's a matter of law, no matter how much is used or how old it is.

I personally would credit will.i.am and leave the others out.

They all have credits on screen.  They all contributed to the creation of something new that is original to the film.  Sure, some of the contributions are from previous creations, but the current creation would not be what it is without the contribution of the older song writer.  I would credit them all.

For the time being, I've chosen not to include these two songs in my contribution to Blu-ray profile UPC 883929243815.

We should only count the song’s writers, not the writers of any material that’s sampled within it.  This is because the music in films is one of the things I’m especially interested in and for my own database I collect all the song writer and performer information for all the music and songs used for all the films I watch; this takes a long time to do.  However, I don’t include information relating to sampled music.  If this became acceptable online, I... would... cry...    So I’m appealing to everyone’s good nature, soul and moral compass; keep info regarding samples out of the online, because that would be nicer for me.

This has been a party political broadcast on behalf of the I’m the Centre of the Universe party.

Paul

Having some background in music myself, I know that credit where credit is due is a huge deal. Look on the credits for nearly any rap album, and you'll find James Brown or George Clinton because beats they created decades ago are often the basis for new tracks. Those who don't give credit and get sample clearance get sued, period. Often times the credits will read something like "contains a sample of _____, written by _____". Other times it just lists em as if they were in studio working with the main artist.

So even though many may not even like what has been with their music, they all get writing credits and it doesn't matter how old the sample is, or if the original writers are live or dead. I realize this an apples to oranges situation, but I'll throw that info out anyway to help make a final decision.