Personal Finance Canada

It's a long story I'd rather not get into, so I've simplified it into a single long question...

Assuming a will is valid, but circumstances have changed dramatically since the time the will was written, and there was no opportunity for the person to re-write the will due to incapacity, is it possible to renegotiate the distribution of the proceeds of an estate with other beneficiaries?

Just wondering aloud if anyone's been through this.