Book about two siblings who share a body and solve crime

I never read it but forgot to note it down on my tbr

From what I remember of the description it's about a brother and a sister who were cursed to share a body. I think it's a Victorian-early 1900s period piece and they're PIs. The sister is kind of crazy and reckless and the brother is more careful. It's a newer book, I think published in the 2020s

I want to say there's a tea-room motif but I might be confusing it with a different book I saw recently