Hi, we are in the process of doing it as a family of 4. You need to do the main visa first and then when you receive that visa, you can apply for the other visas. For the dependent, they ask you to upload proof of relationship (birth or marriage certificate) and the main visa, as well as financial sponsorship and bank statements, and proof of location (hotel booking, entry stamp of the country...)
we wrote Pau France (in the passport it said Préfecture des Pyrénées Atlantiques PAU). A few friends said they wrote that down so we tried that and it worked
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