Parenting issues tend to come up whether you're married or separated. Children are hard to predict, and there may be a time when you have trouble working together to figure out the best way to handle your kids' discipline or other issues.
When you're separated or divorced, handling parenting issues can become even more difficult. One parent might penalize their child for their actions, but the other parent might not hold up that penalty at all, despite the punishment including being grounded or restricted from certain activities. With shared custody and visitation that overlap, it's a reality that punishing your child can become complicated.
That's why it's smart for you and your ex-spouse to work out a plan for punishments. If you want to ground your child from certain activities because of their behavior, for example, then each of you may want to have terms under which you'll uphold that punishment during your time with your child. Otherwise, undermining each other may send the wrong signals to your child or children.
It might be hard for you to agree on how to penalize your child for their actions, but it is in your child's best interests for any punishment they're given to be followed through on (as long as it is reasonable). For instance, if they stole, having to pay back the cost of the item before they can have the item or being banned from the mall for a month would probably be reasonable. Both parents should work together to uphold reasonable punishments so that their children learn right from wrong and can move forward.