Decisions are made by consensus, but even then there is no legal framework to enforce any decision against a country that changes its mind. However, there is a unique family relationship between the Commonwealth countries which allows relations between them to be conducted in a friendly atmosphere for the most part. Indeed that friendly co-operation is helped by the fact that there is no compulsion. The Commonwealth is no so much about power as co-operation. For example, many professions and institutions in the Commonwealth have common origins.
Groups linking such professions and institutions flourish.
Such things form the 'unofficial Commonwealth' of professional associations and non-governmental organisations. They have been joined by many more. Also there are countless related sites to be found throughout the Web.