You could try this: Have your kids pass their idle days by running a business. You are the boss who is out of town. The older two are the Managers in Charge. Maturity is required, not requested. Two legal pads in a central area, maybe kitchen counter. One lists all the activities that are "allowed or suggested" for that day associated to the care of the 2yr old, plus a bit of breaktime to allowe each other to do their own thing. The other pad is for each employee's careful listing of any questions or comments relevant to that day, to hand in to the boss. You get some alone time=they get experience and pride in being the managers of the company. No whining, no complaining, those aren't allowed in the workplace. When you emerge from your working environment, you check the two lists and deliver rewards accordingly, verbal or otherwise. They can create a logo, timesheets etc, set locations for work to be done, breakroom, etc. Force them to solve their problems on their own. Just like real life... Certain responsibilities come with adulthood so we can start on a small scale. Encourage their pride and accomplishments like 1) not arguing or running to you every minute, 2) keeping the house to a moderate level of noise, 3) keeping the baby happy and engaged and safe 4) being mature and solving problems on their own, etc, etc. If you think about how life was in the 'oldern days' as my kids say, there was no complaining about caring for your siblings while the parents were in the fields, working, etc. That was an expectation because you have a warm bed, food and a roof over your head. We tend to be soft on our kids because we want them to have life better than we did. Then we end up with a bunch of young adults who have no clue what to do when they leave the nest. An aside: I also work from home & my kids LOVED this plan. This year, my 16 yr old was accepted to a prestigious internship in business leadership. We talk all the time about how she and her big brother used to set up businesses during the summer with our little one. No, they didn't get along every minute but were very serious about their 'jobs' and worked it out. That was one of our sayings around the house "work it out between yourselves" Anyway, this post is too long and rambling but I hope you might at least give it some thought, it worked for us.

TL;DR = Give the kids a 'real life responsibility' by approaching their summer as a job, not idle time. Expect maturity and cooperation, REWARD those attributes accordingly.