A practitioner asks: “I wonder if this additional wording in step 9 of the Protocol can be helpful, ‘Source Creator, invite the higher self of my clients to assist Creator in bringing new instructions to their cells, tissues, and organs from a future time of youthful health and wellbeing to heal and regenerate them as needed.'” What can we tell him?

This is not truly the addition you think but rather would result in a diminishment in some cases. There are more aspects to your makeup than the physical body defined by the scientific terms you listed. There are energetic layers as well, and so restricting this to getting help for the physical aspects of the being, it can be seen by the divine realm as a restriction to the physical alone and not to the higher vibrational energy layers surrounding and interpenetrating the physical body per se. There are many aspects of the living organism that are not understood as yet by science, so this is an example of how more is not always better in terms of wanting to be all-inclusive, but using a partial list of criteria only, you can set a trap for yourself in doing so.