Responses
I think it's http://www.mangago.me/read-manga/hana_no_mizo_shiru/
and the frilly dress happens in the sequel http://www.mangago.me/read-manga/hana_no_migoro_ni/
oooohhh!!!!! so much!!!
link, please! its a yaoi manga. there was a chapter about the seme who brought the uke to his family introduced as a friend. then seme's sister dressed up the uke with frilly clothes. there was also a scene where the seme also introduced to the uke his fostered cat who stilll sleeps on his bed even he's no longer staying there. sorry for these vague clues (●￣(ｴ)￣●)