How should a step-parent handle discipline?

The first opportunity you have, get the Father and the child and you in the same room. Let it be clearly known that you and the Father are on the same page with regard to discipline, etc. Once you and the Father agree, and the child understands, (and they do understand), then let the ex know that you have had the conversation. Take all ammunition the ex or the child may have about you and the Father agreeing on discipline...then follow through and be very consistent..and you will be rewarded with a supportive mate and a well behaved step child...no try it