I've done this several times and only had an issue once.where the hotel (a Sacramento area Marriott) was very aggressive, said they would upgrade the room when I arrived at the hotel and would re-key the key for lounge access when I arrived. Every other time, there has never been a problem. I normally have my guest added to the room through my ambassador but also have increasingly been using the chat function in the app to communicate with the hotel which is another option.