We had a family day like that. And it was this time of year, so there were many barbecues. :) Not always. Often a theme with decorations and silly songs to well known tunes, and almost always in a backyard. You didn't mention location, but your menu makes me think of "park".

What you've lined up sounds good, but unless you're absolutely sure of your people, you might want a sign-up sheet. Very easy to do nowadays with e-mail or a text chain. This avoids all bringing mac & cheese. :) Instead of just "bring a salad", you can make a list longer than the number needed so they have choices, and maybe one or two "mandatory". Someone has to bring a green salad and someone has to bring potato salad, and the rest can choose from slaw, pasta salad, "Asian" salad, Italian chopped salad, carrot salad, Ambrosia, etc., and have a write in. For the deli platter you might want to list a "feeds X number of people" or a price, so people feel like they're contributing equally. Or maybe I miss read and you meant pitch in money for you to provide the deli tray, which works best for the same reason.

If people want barbecue but don't want to do the work, consider buying it from a good barbecue place. They often have "family meals" or catering. Or a food truck.

The biggest issue with parks and coolers is food safety. Not a great place for cooking. The one thing that usually works well on a park provided grill is a weenie roast because the sausages are already cooked and only need to be heated.

How hot and humid is it there? It's dank here at this time of year, so lighting a fire is nice.

I am a bit lof a control freak.....I want to do iyt all and have control over what and how it's served.

As fot "spending all day BBQ ing"...what? It's either a large hunk that goes on low and slow and doesn't; need much attention for sevral hours....or its burgers and bratsw hich cook in about 20 minutes....It's no trick to make a huge pasta salad like a mastaciolli, easier than peeling 10 ppounds of potatoes, and a veggie salad......and perhaps have people bring buns and chips and cookies and ice cream

Maybe 'all day' is a bit of an exaggeration, but it can sure feel like that when the weather's hot and you're stuck next to the grill.

What about desserts?

Yes, do ask folks what they want! I'm not familiar with the place, but it sounds great. I looked at the Google weather graphic and this week it looks similar to here—not too warm and cloudy. We also usually get a blistering heatwave in June, with the rest being dank. If the kids are going to be swimming, they might want a warm meal, which could easily be hot dogs (sausages), which are quick and easy on a hibachi if you have to bring your own (and more compact to carry in than deli trays), or even soup in thermoses. If that isn't a concern, I'd think the sandwich makings and salads to share plan would be nice at a place like that.

I suddenly have a lot of family coming here this weekend, and trying to plan meals around the comings and going of the various people will be problematic.

A friend suggested getting a couple of already-grilled tenderloins from the local Market. I got two that, hopefully, will be rare. They will be ready-made whenever/whoever needs a meal. I plan on that being the main meal on Memorial Day... sliced thin and made into sandwichs each their own. If someone wants it hot, then the "rare" will heat better.

It sure will be fun to see everyone. My tail is waging and I'm, unsuccessfully, trying to keep it hid. 😁