Bear in mind that an owner can nominate themselves but can’t be nominated by someone who is standing for election. That means you can’t nominate your friend (but you can vote for her and yourself and use her proxy to do likewise).
Also, co-owners can’t nominate themselves but can be nominated by the other co-owner.
Basically, you need a letter from the other person, nominating themselves (or from their co-owner nominating them) plus a signed and dated proxy form allowing you to vote on her behalf.