I need advice: My stepdaughters (6 and 8) are exhibiting negative traits that their father has.

First, my wife and I are asking this question together. My wife's ex husband isn't a man of moral character. Constantly lies, schemes, and manipulates people around him. We have noticed that our daughters are modeling these characteristics of their father. To extreme cases, the oldest pretended not being able to read so she could try to be moved back a grade which her cousin was held back in.We have seen these behaviors increase over the last 6 months. We discipline our children through grounding to time outs. Their father doesn't discipline nor holds them accountable to their actions, even after him agreeing to be on the same page as us in disciplining them.The question is, how do we address this? We encourage all their positive qualities every chance we get, however it's just getting worse.Thank you all for your advice and wisdom. via /r/Parenting http://ift.tt/2dzsKiX