How can there be most happiness?
Happiness is a difficult subject with many aspects.
Existence of individuals who can experience is a necessary precondition for happiness.
Creating conditions for as many individuals as possible to exist on earth therefore goes a long way towards maximizing happiness. That does not yet require to make assumptions on how each individual achieves happiness. It would seem to be a motive shared across different cultures and beliefs.
Happiness has value. My own and others' happiness. Let us value happiness and try to create the most of it. The amount of happiness increases as long as there are self-aware beings alive. Let us help to find ways for civilizations to continue. The better these civilizations are at helping the individuals be happy and the less distress they cause, the better of course. To determine that, however, requires assumptions on how such civilizations function or how they should be organized, which even in the present is a rather contested subject with many aspects. No matter how civilizations function, to contribute to creating the most happiness, they must allow life to continue. Therefore the focus on these pages is on the ability of continuation, by looking what follows from the assumption that there is at least one civilization on planet earth in a billion years that evolved from currently existing human civilization(s).