[YAC]POS causes POW orphan issue

[esuncloud]

In ZcCoin, I found that the POS will cause lots of orphans in POW periodically. ZcCoin is based on YaCoin, and is there any similar issues in YAC?
The problem is that even though the POW block has been confirmed for more than 520 times, it will still become orphan when the POS comes out. Any idea how to solve this problem, or is there any similar problem in YaCoin? Thanks.