If your mother has legal documentation that she adopted your foster brother, then he can be included in your application for citizenship in St. Lucia.
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How can I include my foster brother as a dependent in my Saint Lucia citizenship application?
I have a bit of a complicated family situation. My mother is over 60 but she is a foster mom of a child now aged 16. I want to apply for the St Lucia passport and include my mom but not sure how the process would be for my foster brother? Would I be able to include him at maybe an extra fee or is it not possible at all?