Step Brother and My Dad's 80Th Party

I would just send a breezy "reply to all" like this:

"Hey (Step-brother) thanks so much for checking on the plans. Because you already agreed to do the food we didn't want to bother you with the remaining details but rest assured that everything on your list has been planned. Great minds think alike because what you suggested is what we sorted out."

If there is anything on the list that wasn't already assigned or needs editing, add something like:

"Just to avoid confusion, I have slightly edited the list below based on past discussions. If anyone has any questions, please let (your sister) and me know. Thanks so much - we really appreciate that we've all been able to work together to plan this special day for Dad!"

Then leave it at that. No need for hurt feelings here.

I would let it go. I'm amazed so many people are willing to help out, personally. In response, I would say, "Thanks for making this reminder list for us all. I know we are all looking forward to making Dad's birthday great!".

Be honest. If you feel like changes need to be made make some edits to the list and say "I had already spoken with so and so and asked them to bring xyz. I"m sorry I failed to let you know we had this covered. Thank you for putting this together, please everyone make notes of the changes".

Leave it at that and move on.

Complain here. I would make fun of their annoying habits to your husband/boyfriend or here. If you have kids do not involve them. You never know what they will say and to whom (oh wait, that goes for your boyfriend/husband too). It sounds like he forgot to include your sister on the email.

I'll admit my reaction is not the most mature.

Just reply by saying..."I'm on it"! And let it go.

I'm not quite sure what the problem is, but you could always respond by saying thanks for send out the email, mom and I had it arranged exactly how you sent it out.