@ruben1979 When it comes to the kids helping with cleaning, there's of course stuff they just aren't capable of doing to an adult-level expectation, but 9-11 year old's are capable of a lot. It might just come down to training them and encouraging them to do a good job.
Every day, every morning, chores need to be done before you guys leave the house/start the fun stuff for the day. There's no TV/screen time until chores are finished.
If they want to do something the next day that would involve an early start... then the next morning's chores can usually be mostly shifted to the evening before.
I would suggest a chore chart/list for each kid. The chore chart/list should include pretty detailed steps/instructions (or maybe something separate with that one it), so that you're not dealing with "I forgot" or "I don't know how" all the time. Give some thought to which chores they are assigned - you want to find a good balance so that they are actively contributing, but you don't want to give them chores that are simply beyond them.
You'll run into days where chores don't get done, and the day's activity/plans never come to fruition. Or days where the kids are slow about getting their chores done, so their fun activity gets cut short. That's FINE. That's a life lesson. It is really important though that their fun activities do not occur until chores are finished...and this includes playing outside, playing with friends, screen time, arts and crafts, etc. If they don't want to do their chores, they can sit in bed, doing nothing.
You're a SAHM, not a maid/housekeeper. You contribute to the family chores, but so do the kids, because they are part of the family. Obviously the babies don't really contribute, but that's because they are babies. Your older ones didn't contribute when they were babies either.
Another thing to consider is whether or not the family has too much "stuff." When you have kids, especially when you have kids whose ages span a considerable range, its easy to collect a LOT of stuff, that seems necessary but probably isn't. Especially as your infant twins start to get a bit older and more into toys, take note of what toys they are actually playing with, and what toys they aren't playing with but keep ending up on the floor because they get thrown out of the toybox when looking for the toys they are actually playing with. You can try rotating toys too, where a bulk of the toys are kept in a bin that's out of the way, and every 2-4 weeks you rotate some/all of the toys. Keeps things cleaner and keeps the toys interesting. Same for the older kids, I've had a lot of success in getting older kids to let go of items when you explain that having fewer possessions in their room/toyroom makes cleanup much easier.
There's also room for compromise in how clean/organized things are going to be during the summer. Think about the chores that could be done, and then which ones are most important. For example, maybe right now you spend a fair amount of time folding and putting away clothes for the kids. First off, 9 and 11 year olds are capable of doing their own laundry with only minimal supervision. Second, if they don't care about their socks being matched or folded, or their play clothes being wrinkly, then that's OK. If your husband is finding it very stressful to work from home with a cluttered house, that makes sense, so think about what rooms should be a priority. Kids bedroom doors can be closed, and your husband shouldn't need to be in them much during the day. He probably does frequently see the kitchen and living room though, so maybe those are kept up better. And, maybe he needs to step up a bit more too. These are his kids as well, and during the summer you just don't have as much time. What things can he take over doing on a temporary basis?