Shalom respected Rav
What do you mean when you write that “it is necessary an official acceptation of Seven Commandments of Bnei Noah”? If a person make a decision to follow Seven Commandments by himself, will he be considered as a Ben Noah before God? Or it is necessary a formal procedure – like it is obligatory for a conversion to the Judaism?
To be Ben Noah it is necessary an authority group of three Rabbis who consist the religious court – so called Beth Din. They can make such a decision if a appropriate request is received. In International Centre Bnei Noah (Brit Olam) we have a group of Rabbis who well-known such a procedure.