In fact you can. With no other formal agreement in place, any cooperative venture is an equally-owned "general partnership", and no partner can legally do anyth

In fact you can. With no other formal agreement in place, any cooperative venture is an equally-owned "general partnership", and no partner can legally do anything to diminish another's ownership. And all business debts, however they are incurred, are shared equally too. Source: been there, twice. Now I keep a boilerplate partnership agreement form URL bookmarked on my phone...