〜とあれば
if it's (for), if that's what it takes
Noun / Plain form + とあれば
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とあれば means "if it's for X, if X is the case", and it's followed by a willingness to do whatever it takes: 子どものためとあれば、どんなことでもする, "if it's for my children, I'll do anything".
The first half is usually a special reason: someone important, a request from someone you care about, an order, or a need. The second half shows readiness or resignation: する, 従うしかない, 断れない, いつでも手伝う.
It's a more formal, emphatic version of なら. Don't confuse it with とあって (N1), which gives a reason for something that has already happened: 連休とあって混んでいる.
Examples
子どものためとあれば、どんなことでもする。
If it's for my children, I'll do anything.
社長の命令とあれば、従うしかない。
If it's the president's orders, we have no choice but to follow them.
必要とあれば、いつでもお手伝いします。
If it's needed, I'll help any time.
君の頼みとあれば、断れない。
If it's you asking, I can't say no.
彼女が来るとあれば、僕も行こう。
If she's coming, I'll go too.