That shouldn't be a problem as long as you and the doctor agree. As @johnbishop suggested, I would call to confirm. As @IndianaScott mentioned, depending on the information shared, you may have to sign something to give permission for information to be shared with your family member.

I know I've heard other members talk of doing this, but can't recall who it was. My mom and I do this with her PCP when I can't make the trip for her appointments. I works like a dream and I didn't have to sign anything. Sometimes I attend in person, other times by video call. We use Facetime too.

Please let me know if you find out anything that will help inform other members.