Yes you are right. They have the Canadian passport too...so I feel without anything to show lol but yes probably better to wait.
I thought you had a year to pay that green card fee anyway..why would this be a final notice 3 months after approval.
Update on our journey..husband and son are here. Applied for my son's passport in March and still waiting. Just got a final notice to pay the green card fee. Would you wait for the passport to come or just pay the fee and get the green card too?