You should hire
https://compassionatecoding.com/.
Basically, there shouldn't be conflict. There should be polite disagreement, with people listening to each other, understanding where the other side is coming from, and coming to a consensus or coming up with way to decide.
If you don't have that the issue isn't lack of a system, it's a people problem about how people interact. (I write about it from individual's perspective here: https://codewithoutrules.com/2018/03/09/win-technical-argume...)