and his estranged wife put aside their differences for a special celebration. On Saturday, August 6, the "" star reunited with Robyn at the 10th birthday party of Guatemalan twins who were connected at the skull before being separated during a 23-hour operation at UCLA Medical Center in 2002.
Helping to celebrate Maria de Jesus and Maria Teresa Quiej-Alvarez's milestone at the Hawaiian-themed bash in Malibu, the 55-year-old actor told PEOPLE, "We're all involved in Josie and Teresa's lives." He added, "It's incredible seeing Josie and Teresa do so well. Listening to Josie speak, you think, 'Man, this is the happiest kid I've ever seen.' "