While she cosied up to her co-star Michele, 34, who looked typically dashing ... a number of other actresses of all different ages, all dressed in identical outfits to herself.

Blake Lively's co-star Michele Morrone looked nervous as she appeared ... but I think it’s time to stand up for a person that I really love and this person is Blake Lively.' ...

"Michele said she was very nice, and that was the extent of it." A separate source also tells PEOPLE that the Keeping Up with the Kardashians alum had "never met [Morrone] before" this weekend.