family name

I ask.

私は尋ねます

I ask the other person's family name.

私は相手方の名字を尋ねます

I ask the other person's family name at the reception desk.

私は受付で相手方の名字を尋ねます

I ask the other person's family name at the reception desk during registration.

私は登録するときに受付で相手方の名字を尋ねます

I ask the other person's family name at the reception desk with my coworker during registration.

私は同僚と登録するときに受付で相手方の名字を尋ねます