I read this book in the last 2 years, it was about two men, one of them was health care professional. They have this friend group and each person in the group has a book for them. I think the other one is a lawyer or something along those lines.
In this book, there are two children, a boy and a girl. Their mother overdoses and their aunt take custody. One of the MC is much younger I think. So the aunt is pretty cruel and the boy comes to the hospital to talk to the MC. Somehow both the MCs are in the hospital and the aunt comes there with a gun and shoots the main character that is not the health care professional, and it turns out the aunt is his ex girlfriend. The MCs survive, and adopt the children.
The children bond with the MCs friends children and it a hea.
But there's a prologue about a future book where the son is estranged from the couple, only in contact with his sister. The sister calls about some birthday/anniversary celebration, the son has a female fiance.
The son also kinda idealises one of the friend's child (a boy) and follows him around.
I think it was a fourth book in the series, I'm not sure. I might even be confusing two books, but I r ally want to find the son's book.