How do I maintain on myself as the project focus when my many team members do what they want and talk around me to each other?
Ignored in Massachusetts.
Some people's initial response to your concern might be, "Wow! Need the spotlight much?" but your concern is completely valid. A properly set up team has the Project Manager in the center, surrounded by her core team who represents the various functions required by the project. On larger projects, there are extneded team members assisting the core team in one or many of these functions. On really huge projects, there could be additional layers of extended teams. The theory is that no-one can effectively manage more than twelve people.
So when you have one of these large teams, there is a large number of possible communication channels. Let's examine that. Between two people, there is one communication channel. Between three, there are three, once you get to six people on your team, there are fifteen ways people can talk to each other. You can draw these channels like this:
If you have a team with seventeen members, how many different ways can people communicate with each other? For those who want to do the math, the formula is at the end of this post. The answer is that there are 136 possible communication channels among this team. And the odds are good that few of these channels are made up of people who know all there is to know on the project. And most of these channels bypass the Project Manager.
You, as the PM must show this logic to your team and then insist that all Communication passes through you. You may be aware of a complication that QA might have on a solution proposed between R&D and manufacturing. You must be the focus of all communication.
Practically, what you need to do is establish a set of ground rules for the team at the first meeting, covering meeting times, talking over each other during meetings, etc, and ensure that this set of ground rules includes the communication channel story. Then ensure that all communications work through you, as shown below:
Oh, and that formula. Here it is: # Channels = n(n-1)/2 where n = the number of people on the team.