The kids play while I do my things like make lunch. At the same time if my group is in this stage then I would bring them into the kitchen and set them up at the table to do an activity where they could be monitored. While they are having morning snack I do some prep for lunch.

When you are with them you might want to use a sterner voice when this kind of behaviour happens to reinforce that it is not allowed. If you watch the group you may find who the instigator seems to be and that child could be either taken with you or the kids removed when an issue does arise - lets them know you have eyes in the back of your head,lol. Also I will sometimes remove certain toys while I make lunch so they are limited to only a few so clean up when food is ready is quicker but also removes the most commonly fought over toys.

My gang learns very early on I don't tolerate their crap so by 2.5 if there was an issue they know they would be sitting on the kitchen floor sulking till lunch was ready so rarely challenge it. Even by 18 months they know my raised voice means don't do it again. Having said that there are just some kids and some groups of kids that don't get along for some reason. You might even have to do some actual training where during freeplay you step in before issues happen to teach them what to do such as it is ok to put your hands out to protect your personal space - prevents getting bit. It is ok to play alone and the others have to sit by quietly and wait their turn or find something else to do in the meantime, those kinds of things. As language comes the kids will start to use the words they have heard you using in similar situations such as sit down, it is my turn now.