Would there be added value and would it be allowed to ask benevolent extraterrestrials to assist us by adding their intentions to ours, as well as doing healing sessions for humans and their perpetrators on their own?

The moratorium on interference by benevolent extraterrestrials to work on your behalf to tip the balance applies with regard to healing as well. This is a burden for humanity. You are doing a good job of ferreting out the various adjunct sources of healing power that might be invited to participate and then enlist their help in appropriate ways. That is very beneficial to the cause and will, in fact, make the difference, but that only extends to those already in earth plane with an ongoing involvement on a regular basis in many ways with humanity, or the interlopers, or both. The benevolent extraterrestrials are bystanders truly and have an interest in the human enterprise indirectly, but are not appropriate to be working on humans or their perpetrators. The makeup and energies are different enough that many things they might do will not be applicable as they are higher dimensional beings and not in the physical, so they are also not the best source of expertise in terms of gaining information and knowledge, and understanding divine perspectives about many things in life. They have things they can say and are useful, at times, to offer warnings and to help human understanding of things going on and what can be done, but that is not the same as doing deep, elegant healing that may well be crucial to the task. There is a huge backlog of healing need that must be reckoned with ultimately for human progress. This cannot be done by other extraterrestrial groups than those you have included in the list within the Protocol already.