Hi Eve,
do you know [https://www.meta-health.info|www.meta-health.info]?
You find answers to most of your questions there.
The global organisation holding the trademark "META-Health" is META-Health International CIC (MHI), having been founded in 2017 after her progenitor the International META-Medicine Association, for to be able to carry out the interests of the META-Health community with a democratic structure. The term "META-Health" was coined by Robert Waghmare, to be focused on health instead of on medicine. Read about MHI [https://www.meta-health.info/organization/|here]
The IMMA itself had been founded in 2004 by Johannes Fisslinger and Dr Anton Bader, who wanted to develop the holistic medicine model with the contemporary understanding of  psychosomatic medicine incl the biologiocal model by Dr Hamer, body-mind-social health and ways to help and influence health based on these grounds