As a harper and also as someone who has recorded and dealt with copyright/royalty issues, I'll throw in my 2 cents worth. I know what you mean about 'building your arrangement' from the bits from a book and bits from someone else and bits of your own style. It's the Frankenstein model of harp playing. I do it all the time.

As for recording it...I'd honestly suggest that you ask the opinion of a serious recording folk harpist, such as Sharlene Wallace or Kim Robertson, before you do anything drastic. The wording you use on your published recording CAN make a difference - you can't just throw around words like "arranged" or "traditional" if you aren't able to back up those claims down the road if needed. Your CD may end up getting airplay, or sold in stores or clubs and so you need to do it right. Your intent is to be clear about the construction of the music - its melody and harmony parts, to pay royalties where royalties are due, and to give credit where credit is due.

I think it's important to get this done right before the CD comes out, rather than try to fix it later.

MHO,
~b.w.