Actually, that's been discussed here in various threads for some time.
Being able to filter by DVR (so that kids, for example, don't see the contents of the parents DVR) has been a desirable capability mentioned by others.
This is similar to the problem I'm having with reluctance by some here to the prospect of MRV (not installed yet). Particularly so for a house of adults with their own boxes in bedrooms or some other as in my situation.
They are not exactly high on sharing the full contents of their playlists, and consider MRV as allowing for snooping.
If they have recorded things like "Adult programming" you get the idea.
Instead of a simple all or nothing Share playlist option we really need the ability allow individual programs by check box to be shared or not.