The mission of the Holy Prophet (pbuh) was to deliver the Divine Message to all his addressees. They in their collective capacity then carried the burden of delivering it to the world of their time and their subsequent generation. I cannot accept the notion that the Prophet (pbuh) kept the knowledge of certain religious directives to a few individuals only.
You seem to be implying that the Prophet (pbuh) gave additional religious directives which were independent of the Holy Qur’an and The Sunnah. This then would imply that the Prophet (pbuh) did not completely deliver the Message and thus failed in his mission. We know that this is untrue. So, it is important that we interpret the Ahadith in the light of the Qur’an and the Sunnah rather than vice versa. Only those Ahadith which have a basis in the Qur’an, the Sunnah or the inherent nature of man, can have any relevance and that too only of a supplementary nature. On the other hand, those Ahadith which present directives independent of the Qur’an, the Sunnah and the inherent nature of man cannot have any significance for us.