[JamesCH95]

It sounds like you need to have a calm team-wide meeting to discuss how you would like your team run. Establishing a clear process for design decision making is one of the more important facets of running a smooth build season. Another good policy is immediately disowning any idea as soon as its presented. It's not "Joe's Idea" it's "the doober mechanism." This helps divorce ego from the design decision process.

Another thing for your team to consider: not all adults make good FRC mentors. I have seen barely-competent mentors be so insistent and obnoxious that they drive truly great mentors away, much to the detriment of the team. I wouldn't suggest doing anything rash, but if there are one or two people that appear to be at the root of many conflicts they may need a "shape up or ship out" sort of talking-to, probably from an adult team leader.

It might also be worthwhile reminding everyone on your team that both giving and receiving criticism and correction graciously and professionally is one of the greatest and most difficult talents that a technical professional can develop.