Responses
not sure if this is it, but the story sounds vaguely familiar to this one; http://www.mangago.me/read-manga/tied_up_in_twins/
unfortunately no ☹ basically the twin(teacher) went in place of his twin to go in a date because he doesn't want his brother to get hurt again, but the other guy(uncle) also went in place of his twin(the father of the kid). So the pairings were unclexteacher, the fatherxtheother twin
what's the title of that one yaoi manga which the guy is gay and then he is taking care of the nephew of his crush(which he doesn't know that, that guy has a twin) which also that kindergarten teacher also has a twin