anybody got kids, past or present i got questions

That's funny because I'm the only one that can keep my grandson in line.
My son never gave me any problems, I told him to do something, he did it. My daughter (step) was in good shape until the divorce. She went to hell in a hurry. I was able to salvage my son, but wasn't able to have contact with the step daughter. She now has kids she cant control.
You're probably dealing with some jealousy issues if you now have a baby. They may be looking for attention, positive or negative.
There is no good fix, assert you control with the 8 month old and good luck. the other two will get better as they get older, as long as you remain a good role model.
At 44 your stronger man than me.