She asked me and one of my friends to hang out so the three of us are supposed to meet somewhere downtown.
One of my foreign friends asked a Japanese friend of mine and I to go out somewhere, so the three of us are planning to meet somewhere downtown.
ーShe asked me and one of my friends to hang out so the three of us are supposed to meet somewhere downtown.
「彼女は私と私の友人の一人を誘ってくれたので、３人でダウンタウンのどこかで会うつもりです。」
このようにプライベートでも supposed to を使って言えますよ。
ーOne of my foreign friends asked a Japanese friend of mine and I to go out somewhere, so the three of us are planning to meet somewhere downtown.
「海外の友人の一人が私の日本人の友達と私を誘ってくれたので、３人でダウンタウンのどこかで会う予定です。」
plan to を使っても言うことができますね。
ご参考まで！
カナダ 
