This is my dream British Sibling family.You all know Professor Layton of course.But the other two aren't as clear to you as he is.So I will explain:

Montmoency-Oldest Sibling
Montmorency, or as his two younger siblings call him Monte, is a former convict turned aristocratic gentleman.Montmorency works legally as a British agent and illegally goes about his adventures as his alter ego, Montmorency’s vile manservant, Scarper. Scarper is a master of the London sewerage system and carries out his business using the sewers as a sanctuary and escape route.
=From the Books Series by Eleanor Updale, Montmorency=

Emma-Youngest Sibling
Emma is the youngest sibling of the sibling family.She falls in love with William Jones from the first time they meet. Originally from a poor seaside Yorkshire village, she was kidnapped as a young girl to be sold to a London brothel. She managed to escape, but became lost in London. She managed to work odd jobs for food, until she was taken under the wing of Kelly Stowner, as her maid. Under Mrs. Stowner, Emma was taught to read, write, and a variety of other subjects. In later chapters of the manga, it was revealed that Emma could also read a bit of French.
=From the Manga and Anime series of Emma by Kaoru Mori.

Hershel Layton- Middle Sibling
Hersehl, the middle child is the peace worker amongst the siblings,is an English gentleman notable for his skills at solving puzzles, as well as his signature top-hat.
=Layton from the Professor Layton Series by Akihiro Hino=

And that's about it. XD