There isn't one listed in the OP. I don't know if that's impossible, or hard or easy to make either. You can send a PM to HYPERfuture to see if he knows of any.
easy possible just copy that codeparts from a coin that have it implemented
there are basical 3 paths
prevent split stake by set a minimum split size (meany if coin pile below split size it wont split into two)
auto merge piles smaller than trigger value into one bigger pile
and last but not least true zero usermaintainance way with wallet code choose coin split and coin merge automatic
(example DMD Diamond POS here their POS is explained: https://bit.diamonds/community/index.php/topic,127.0.html )
I vote for DMD's. That is an awesome system and makes things so much easier. As it is, I have to keep merging piles (and you lose coins doing that since you either have to sit and do it right after a split or you have coin age built up that ends up lost after).