The switch that combined homes

Harry nor Louis had no idea that the day they both gave birth, that it would eventually lead to a love they didn't know they needed. 5 years later, after one child becomes ill, only then does Harry find out that the daughter he thought was his own flesh and blood, actually isn't. This is a story of how two babies were accidentally switched at the hospital, and now two already attached parents must figure out how the hell they are going to 'let go' of the child they already love.
Or will they have to?