My keyholder is away and wants to hand me to a friend of hers for a week

My keyholder is away for nine days somewhere with almost no signal. She has suggested that rather than unlock me for the duration, a friend of hers who is also into this could hold for the week.

I have met the friend twice at social things and liked her. I am not opposed. But this has never come up before and I have no idea what you are meant to sort out in advance, or whether the sensible answer is just to unlock for nine days and stop overcomplicating my life.