I did try to surf the forum for this beforehand but couldnt quite seem to find what I was looking for...I intentionally want to keep it general to understand as many experienced points of view on the topic as possible.

I have been co-parenting (not married) my partners daughter for about 3 years. 

We regularly have disagreements that ultimately end with no compromise. Argubally they seem unresolved. I try my best to talk through them but my partner seems to exhaust the topic and it does not get re-opened.

This is especially prevalent in my daughters increasingly bad behavior. So the boundaries of parent to child are very blurred. It becomes quite a bit frustrating when my partner decides to over rule any cooperative decision making on what I think are normal things like bedtime consistency, cut off on sweets, or if our daughter has fits she will ultimately support my child’s tantrum.

So my question: If you are a step-parent and you run into issues with your partner not sitting down to discuss who you can jointly organize your families principles, is there a correct approach to make yourself heard? Or do I accept their position and ultimately move forward with their concept and approach? 

Let me know if there is any way I can clarify.