as best one can

as far as one knows

To the best of one's knowledge, as far as someone knows or possible information to be gathered about the topic, subject, aspect, or situation.

back to square one

Located back at the start, as after a dead end or failure.

beat as one

To share the same feelings.

become one flesh

To join together in marriage; to develop a unifying bond as a result of marrying.

best bet

The best proposal or plan.

best laid plans

A proverbial expression used to signify the futility of making detailed plans when the ability to fully or even partially execute them is uncertain.

best of both worlds

A combination of two seemingly contradictory benefits.

best of the bunch

The best or most preferred person or item within a group.