Plenty of the advice you were given has been revised, and plenty of it was right all along. The book covers both, without treating you like you have forgotten how to hold a baby.
What the current guidance actually says, and why some of it changed since your children were small.
How to be useful in the first weeks without taking over, and how to ask rather than assume.
Where to defer, where to speak up, and how to disagree with your own child about their child.
It works as a gift in both directions. Expectant parents give it to their own parents; grandparents give the matching guide to the parents-to-be. If you want copies for both sets of grandparents, there is a two-copy and a four-copy option.