The fighting!

So my 3 yo dd and 3 yo dcb have been going at it for the last little while. A lot of teasing, bothering, fighting etc. I am getting kind of sick of it but I haven't seen much change with what I've been trying. It almost seems like "sibling" fighting.

I really encourage them to solve things themselves and will often respond with "tell ___ " or "use your words." This works for the most part they tell the other they don't like something they did and it stops. Lately they don't seem to care if the other likes it or not so I have had to become more involved. Separating, removing a "hot toy," trying to teach them not to play with the other if they are being mean so they learn how to treat others etc. This works sometimes but maybe I am just becoming less patient but they are driving me crazy! Any other ideas?

PS- part of the problem is that they really only have each other to play with (my other daughter is only 14 mos, 6 yo is only b&a, 2 yo is part time and a baby is starting at end of month). We will go to the school or park so they have other kids to pick from but they continue to play with each other.

When my dc kids fight I make then stand still and hold hands(a min per year) the longer they fight the longer they hold hand...and if it gets real bad they hug for a count of 10hippo. most of the time they start to giggle but if one still fights I talk to mom and dad.