last thing one needs

as best one can

In the best possible way, given one's circumstances and abilities.

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.

be a thing

To exist, or to be available, widespread, possible, or a common practice.

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 thing since sliced bread

Alternative form of greatest thing since sliced bread.

best thing since sliced pan

Alternative form of greatest thing since sliced bread.