Since 美國老土 was in the meeting (I was not), you may still need to listen to 美國老土. :))
However merely based on what you described, I don't think you will get the co-lead role if you just ask for being co-lead.
This is usually how the negotiation goes:
There are total 100 beads on the table, NH demands all and you ask for the fair share of 50, the mediator TS (a new comer!) will try to make peace by giving you 25 and NH 75.
In your *specific* situation, you have to demand to be the sole lead! You can not back down.
In other words, you have to shoot for the higher goal in order to reach the real lower goal.
Another critical thing: don't wait for the meeting. Make sure you meet TS before the meeting and let him know your higher goal. You will not have that communication chance in the heat of the meeting.
