My b/g dts are also 2.8, (also a ds 6, dd 5 & ds 1). I'm dreading potty training, haven't given it much of a go as yet. I find life is getting easier in some ways (abandoning the buggy, sleeping through) but dts do not entertain each other as much as I once hoped, in fact when they are entertaining each other it usually involves some sort of destruction to the house.
I try to think of games/activities that keep them occupied for long periods that other dcs can join in. So we do lots of colouring in/play dough/sticking/cooking etc on wet days and sand/water play or sports day type races on dry ones, these are good days when I feel they all get my time and older dcs like helping out the younger ones and don't feel left out.
They do argue over items so last month I bought a timer and they are learning that when that beeps it's the other's turn, if they carry on fighting item is removed. It's very effective on all my dcs as they immediately see/hear a fair treatment, older dcs are glued to it as it counts down to their turn so stops any unwanted physical action too.
I've taken to removing the tantrumer from whichever room the rest of us are in and noticed a huge improvement (esp with dt2).
I try my best to find at least 10 mins a day with each of them on their own, might be broken down through the day on hectic days. Some times I get more time and I treasure it, but on the days it's the minimum I try not to beat myself up. I do spend a huge amount of my time each day kissing/blowing raspberries/hugging so I try to remember on bad days that I'm not so bad a mum.
Remind your family that all your children equally miss out, dts also have to share you with each other, and that it would be a great help to sometimes separate them, for their sakes as well as your own?