Role of friends and family

If you have made a decision to donate or to not donate, those close to you will be asked if this was your most recent decision. They will be able to override your decision on your behalf if they have information that you had changed your mind since making your decision.
If you record a decision to donate your organs, you will be able to state that your faith is important to you and request that your family/religious leader be involved in the discussions if organ donation is a possibility on your death, to discuss how donation can proceed whilst ensuring that religious obligations are observed.
If you have appointed someone else to make a decision for you, this individual will be asked to make a decision on your behalf on your death.

If you do not do any of the above, the default position from 2020 will be that you will be an organ donor after your death unless you are excluded. Your family will however be able to provide information if they know that you would not have wanted to donate.

Taken from here. Some interesting figures given.