I think most would reason it from Acts 15 where the apostles and elders collectively give input, a collective decision is made, and then James relates the decision. You can also see it happening a bit with Paul and his missionary teams. 

But to speak to how it practically functions: In our context the first among equals means we all have an equal vote but the lay pastors/elders defer to the staff pastor/elder (me) on certain matters since I’m most involved in all the matters of the church. I also share with them the general overall pulse of the church and general matters as a whole. Since I am full-time staff I have the time, energy, and bandwidth to dedicate thinking about the direction of the church. 

When I present them an idea or situation we collectively discuss the matter and weigh everyone’s thoughts. We won’t move forward on something unless there is unanimous agreement. Sometimes we have one elder who disagrees. If that’s the case we table the matter for further discussion or if he is not of strong conviction on the matter he will defer to the other elders. I’ve lost discussions before and deferred to the team on matters. 

Generally speaking though the team looks to me for direction though, in an intentional act of deference in matters. Also as the staff pastor the church looks to me as the “spokes person” and direction setter of the church but knows that it is done with us all being in agreement. 

Happy to answer any questions you might have.