Training group?

While my wife and I were out for a run on Sunday, we had an odd conversation. We are planning on running the Chicago Marathon this year. But the years that we've had our best success is when we had a group of people to train with. However, this year two of our training buddies are becoming new mothers and will subsequently unlikely to take up a strenuous training program. We haven't seen much of one of our other training buddies. And the other training buddy is currently nursing a knee injury. Given the relatively small number of people who would be interested in training for a marathon, we could end up training with one of the groups associated with Fleet Feet or St. Louis Track Club. But we'd rather train with friends than strangers.

Anyone interested?