That's why I said you have to read it lol. It isn't like that; the easy way to put it is that both the father and his daughter merged into one "existence" and they just swap out completely each time under specific circumstances. This leads to the father-in-law spending a lot of time with his daughter's so-called husband and then things pick up from there.
I thought that too before reading, but it’s not the typical “person trapped in another’s body”. The dad IS the dad. When the husband touches the wife, the wife disappears and is replaced with her father. When the father sneezes, he’s replaced by his daughter. They exist one at a time. So yes, this is fully a bl.
Is this actually BL? From the summary, it sounds more like a straight romance to me.