Just tell us you want to be a citizen and pick a territory to be a resident in.
Hi John. I'd like to be a citizen of your nation. I'll also join you as a resident of the Imperial Kingdom of Livonia.
Of course you are accepted and you can be a resident of Imperial Livonia (that's what I call the Imperial Kingdom of Livonia for short).
Hey John! I got your text and I'll join. I'll be a resident of the Imperial Kingdom of Livonia since I live in the same building as you.