Liam Neeson (center), with sons Daniel and Micheal, and Joely Richardson on March 22, 2009
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"They're doing fantastic – as well as can be expected under the circumstances," Quinn told PEOPLE at the Tribeca Film Festival premiere of his film Handsome Harry on Saturday.
The night before, Neeson attended the debut of Quinn's other Tribeca Film Festival movie, The Eclipse. Quinn, godfather to Richardson and Neeson's younger son Daniel, also recently was photographed with the family at a New York Knicks game.
"[The boys] are keeping busy with normal life," Quinn told PEOPLE of Micheal, 13, and Daniel, 12. "I really don't want to say more about it other than that because it's private."
But he did add that well wishes from fans continue to boost the family's spirits. "They appreciate all of the love and support that they've gotten from the whole world," he said. "So that's helping them, too."
