My older brother, his wife, her brother and I all chatted in their room for about two hours last night.
この場合、次のような言い方ができます。
ーMy older brother, his wife, her brother and I all chatted in their room for about two hours last night.
「昨夜、兄と兄の妻と、兄の妻の弟と私で、兄たちの部屋で2時間ほど語り合った」
to chat「談笑する」
for about two hours 「2時間くらい」
ご参考まで！
カナダ 
