When I sent my songs to the copyright office
I used the PA form, and sent my songs as a group, where it says ( Title of this work) I gave the group a name, then I printed out each song on a separate sheet of paper, with song title, and also group title, I then put all in a manila envelope, and sent it.

I was also wondering if it would do any good to have a notary look at your songs, then notaries and seal them in an envelope, not that I worry about my songs, but for those who do.

Emmy