I've downloaded a default replacement package for cat noses (catblackreplacement.package). I've unzipped the file and copied and pasted the .package file into mydocuments, eagames, sims2, downloads folder. But the new default nose colour doesn't show up in the game on cats in the neighborhood or in the create families mode.

Am I suppose to put the replacement package somewhere else?
Is there some other software I need to replace default packages?
Do I need to get rid of the sims2default package before the new default will work?

I have a pc system and all the EP upto and incl. seasons installed. I've not had any other trouble with custom content. But I've never tried replacing default content before.

I'm thinking you probably have it in the game, but it just isn't showing up in your thumbnails. My default replacement faces were like that. What you'll need to do is delete your thumbnails and have the game generate new ones.

Your current cat faces won't change but their genetics will, so their kittens will have the genetics for the new faces not the old ones.

Do you mean the thumbnails in the downloads folder (because i can see it in there), or in the game? How do I get the game to generate new ones? Will I be able to create new cats with the new default noses?

Delete the contents of My Docs/EA Games/The Sims 2/Thumbnails