Will this plan work?

I divised a plan to get sunlight blade and become a Darkmoon +3 as quickly as possible.

First I will get 80 souvenirs. After that I will kill gwyn and use homeward bone to avoid getting an ending. Third, I go to Anor Londo kill gwendolyn and profit. After that I run back as quick as possible to kiln enter NG++++++ and erase sin. Lastly I speed run to Anor Londo join Darkmoons and turn in 80 souvenirs.

Will I be DM+ 3 with zero sin?

No, because if you use a homeward bone it will get you straight to Gwyn's arena.

What if I kill gwyn after gwyndolyn instead.

I wanted to use homeward bone cause gwyn gives me a hard time but this could be a plan B

Wouldnt it just be easier to join the covenant before you go to another play through??