Summertime is a family affair — at least if this week’s parties were any indication. At the premiere of “Ricki and the Flash” mother-daughter duo Meryl Streep and Mamie Gummer hit the red carpet, while Oscar de la Renta’s stepdaughter Eliza Bolen held court alongside Peter Copping at the Save Lake Tahoe Luncheon. Brooke Garber Neidich threw a cocktail party at her son Jon’s West Village haunt, Slowly Shirley . “I think he’s really great,” she said. “The terrible thing is that when he comes home on the weekends — if he comes at all — it’s crowded and things are happening. I look at him and say, ‘Help me with this.’ He’ll say no, and I have to say, ‘I raised you — I’m the one who taught you how to give parties!’” Here, the best party photos of the week.