If an entry in the family book were necessary, our future child would probably have to be entered temporarily in the family book of my wife's parents.
Why not. Both my brothers-in-law and a sister-in-law, all of whom own land without housing in their own right, are registered in my mother-in-law's book as are their children, and in one case grandchildren. As LittleHanoiDreaming points out, it may not be necessary to own your residence to have your own book but it certainly would be inconvenient, as you would have to go through a whole process any time you moved. If you own a house, you presumably plan to stay in one place for a while.Â
Will I also be entered in the new family book as a foreigner (with TRC)?
No, but you will need to be registered as a temporary resident with the local police. The book is a means of controlling the citizenry. They have other ways of controlling you.Â
As I understand from Vn law, to get birth certificate, it is not necessary to have family book.
Wouldn't obtaining a birth certificate necessitate being placed in a family book somewhere? If not, that runs contrary to the notion of government control that is exercised by having all people in the books in the first place. Are there people floating around the country now that are not in any books? To be so would make such persons essentially without the privileges of citizenship as showing a photocopy of the book seems a necessity for so many government interactions.
I recall reading on this website that there was a proposal in government to eliminate the books altogether. Does anyone have a follow up on that? Overall it would be a good idea as the book is primarily a mechanism to control the people going back to feudal China. It is based on an agrarian model where peasants did not, and were not allowed to, leave their home villages for generations.  This is obviously no longer true in Vietnam. The present system results in the absurdity of people living in HCMC while being permanent residents of Hanoi. A modern Vietnam where, unlike China, people are allowed to reside and work where they chose, should get rid of the system altogether. In this day of computer systems, the government could easily have a centralized registry of the citizenry and simply continue having a National ID for all. Perhaps resistance to a central registry replacing the family books comes from local bureaucrats throughout the country, who are not coincidentally also Party members, as they would loose part of the reason for their jobs. That too may change in time. I believe part of the reason for many government jobs in the past was to reward participation on the winning side in the war. Those people are all retired by now.