Hi,
If you reframe your question and ask are my responses, my demands on my kid compatible with his developmental stage, his frustation tolerance level, flexibility, you are asking a great question. Most family usually say parents are too soft and what is required is more discipline , being more conditional and contingent. Kids do behave better around grandparents , there is no emotional baggage , conflict, short visits , but it is great that your kid has a relationship with your mother and there is communication. in my humble opinion we have to learn to generalize the one on one dynamic that exists when we are having fun , the working with - problem solving relationship to the rest of the day. Changing a dynamic to a win-win one from a win-lose one takes time. The idea is to have a relaxed atmosphere so you can work with your child , give him a voice so together you can address his concerns and also put yours on the table , it is not negotiation , but rather problem solving , parallel learning and thinking.
Allan