Thanks for the advice. I agree that I should not be led to be the scapegoat. I've got 8 boys and 1/3 live in 2 households. These parents have equal shared custody. We've only got one month left (our unit does not frequently meet over the summer). So starting in September, I'll be frank with the parents and tell them I will not be notifying 6 extra households of the den's calendar. The parent that shows up at the den meetings will be the primary contact in my book.
On the other hand, I believe I must be more descreet in my dealings with the "other parent". I'll be honest, with so much on my mind between scouting, church, volunteering at school, managing my family - I forget little things from time to time. I can't recall if the one parent told me not to tell the other parent. I do know that she was holding back the info from the scout, for whatever reason. All in all, the family will be moving on and I must too. Thanks.