Good question. First of all:

“[…] the Congolese State now exercises ‘sovereignty’ over lands and resources rather than being ‘proprietor’. The Constitution also recognises individual and collective property rights, obtained either through formal law or customary law.” Long, Cath: Land Rights in the DRC.

In reality, the areas I am working on are “managed” by the local communities. I assume that the decisions where to farm are either taken by the chief of the village or at an even lower level, e.g. the families you mentioned.

I am not entirely sure how thought-out the whole system is and how exactly it works. But if you look at various imagery, you can see that cultivation is shifting - but I don’t know whether this follows a system of a specific number of years.

I have also not been there personally (yet - probably soon though) so I cannot base my assumptions on any personal experience.