I am going to try putting vinegar in my fabric softener dispenser. (greenideareviews.com)
I put white vinegar in my fabric softener dispenser to get the smellies out. (crappypictures.com)
If the diapers did begin to smell, I washed them without detergent, in very hot water, with a half cup of white vinegar (placed in the fabric softener dispenser). (amotherinisrael.com)