Ipod/Iphone music help please

I've got an Iphone 4 that has a selection of music on it that I want to add to.

Now I’m not one who constantly connects their iphone to a computer and the computer it was last connected to is long gone and been told that if I connect to another one and sync it it will delete all the music on it as its library is not contained on the PC its now being sync with ?

The music currently on it is from various CD’s with some borrowed from friends etc so don’t have a back up of them as has they all have not been downloaded are not backed up to icloud.

Is there any way I can back it up or add more music without deleting what already on there?

If you sync from a different computer using itunes you will erase whats on there as you mentioned this is a pain and one of the reasons why I moved to android but anyway
apparently there are programs out there which can help 'senuti' comes to mind. The whole itunes eco system although good can be challenging at times. Good luck!

Usually when you plug in an ipod to an itunes library it isn't synced to, itunes will pop up with a warning, and allow you to connect it and add whatever music you want without removing what's on there.