Hi Frederic,
There are many cases where you can use the INP year member, it is very useful to have it.
you capture into INP member for those data you don't need it in a roll up, and you use for values that will be same for the whole year, so instead capturing per month you can just capture it into INP member once.
There must be a reason when they created in the first place, are you sure there is no data against those INP members?
Andy