AP and how it works? Jaxson and others please respond.

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I was working on H1 when my spouse and kid went for a vacation out of US. They had valid H4 at that time and before their departure I had applied for thier AP. I have received the Approval Notice of AP while they were outside US. I have to join a new employer on EAD before my family joins me in US. My questions: (1) Is it OK for my spouse and kid to return to US using AP? (2) Is it mandatory that one should receive the AP Approval Notice before leaving US? Thanks and regards,