Most laws in most civil law countries (there are exceptions, but it's the standard for the main laws) are a fixed law on a topic which then gets updated. So the 2025 version of the Family Code in France is everything included, and if you do a diff with the 2024 version, you'll see which parts were removed/updated/replaced by which new parts (it could be a clarifying word, new contents, changed rules, etc.). Reading it end to end (it's a hefty book, but still) gives you a complete representation of all laws regarding families (marriage, divorce, kids, etc etc).

It's mostly the obsolete system of common law where to have an understanding of what is legal and what isn't, you need to have a spiderweb of random acts (random as in, they don't have to be thematic, so the Chicken Tax Act of 2005 can have provisions on solar panels that replace the previous solar panel legislation form the STOP KILLING OUR COMMUNITIES Act of 1785) that build/replace on one another, sometimes going very far back, with associated precedents that clarify them.