If it were not clear that she is determined to move away from this area, we would do everything we could/can to keep her here.

[nohabloingleas]

If it were not clear that she is determined to move away from this area, we would do everything we could/can to keep her here.

This is a sentence from the book 'Grammar and Vocabulary for Cambridge Advanced and Proficiency" by Richard Side.

The answer sheet states that "could" as the better option, while "can" is more intuitive for me.

Is "can" grammatical in this sentence, if so, is there a reason for "could" to be the better option?

 

[Piscean]

The hypothetical idea of If it were not clear might well lead me to say If it were not clear that she was determined to move away from this area, we would do everything we could to keep her here.

 

[jutfrank]

The reason that could is the better option is that it carries the hypothetical sense in a way that can doesn't.

Does it help if you read could as 'would be able to do'?

 

[nohabloingleas]

The reason that could is the better option is that it carries the hypothetical sense in a way that can doesn't.

Does it help if you read could as 'would be able to do'?

I understand, but as I see it "would" also carries it, which is why implicating the hypothetical sense with "could" for a second time seems impractical to me.