Forgive me if this is a frequently asked question

It's my wife's birthday in June, it's a significant one.

The plan is to fly off somewhere and have a few close friends join us for the weekend as a surprise. She did the same for me.

The issue is her closest friend is recently divorced and cannot afford the trip.

I have offered to use some of the millions of Avios we have to pay for her trip and she is ok with this.

Question: If I add her friend to our household account and redeem flights for her, will my wife get notified / be able to see her friend as part of the party? The surprise element is very important. I normally handle all boarding passes etc

Thank-you