Fabulous progress and great pics! Your wife definitely is enjoying this game and each time seems to be a more willing participant. So hot that she lets your friend see her with her top open and her skirt pulled up as much as she does.
Think Welee has a great idea: having her wear more sheer clothes when your friend comes over. That white lace / mesh bra is perfect. Quarter cup / open cup bras are also good. As she does not find the lace panties / knickers she has comfortable, why not get her some new ones, a new [or 2 or 3!] lingerie set(s) that would look so sexy and let others see her? You could give them to her saying your friend picked them out for her, or even that he bought them for her to thank her for the pics you have sent him. Maybe then she would feel somewhat obligated to wear them when he next comes over, and let him see how great they look on her... Maybe she should model them for him. Would be really hot if the 3 of you went out for an afternoon / evening of beverages and convincing your wife to show a little more as the day / evening progresses... Love the pics of her sitting out on your balcony letting your friend see so much of her.
Has she worn that white front tie crop top and mini skirt when your friend is over? He would love that, and so would we!
Has she worn that when you have gone out? You have said you want others beyond your friend to see her [and just in case any issues develop with your friend again] and building her confidence to wear sexy clothes when out would help that.
Maybe take her somewhere crowded and others have to press aginst her, a pub or live music or even public transport and get a little separated from her, like what happened with Camflasher's wife... If she has something of a similar experience, and you are very positive and supporting when she tells you about it, it might lead to new adventures...
Wonderful fun for all - keep up the great progress!