Solve one problem and voila here's another

I have a 14month old dcb who has been with me since September. He was a dream child, we bonded quickly and he ate well, slept well, was just awesome all day. between the middle of october and the beginning of november I started my last two kids, another 14 month old girl and an 8 month old girl. firs week with everyone was rough because 3 out of 5 had colds as did I so i figured once everyone was healthy all would be glorious. Not so much LOL. My dream dcb was so miserable with his cold, crying all the time, just all around grumpy so of course i thought it was just the cold. its like he's a different kid. he cries as soon as the other 14 month old dcg comes near him. she doesnt even need to touch him but OMG if she does touch him its even worse. He constantly pushes the 8 month old or rolls onto her if shes near him on the floor but the worst part is how he screams when i leave the room. my playroom is at the front of my house with a huge window, with a set of french doors to the family room which are open but i have a gate set up and another set of french doors that lead into the hallway which are open but also a gate there. so its an open airy feeling and when i walk into the kitchen or heaven forbid i need to leave to use the bathroom he can hear me talking and I always say i'll be right back but he freaks out and I do mean freaks out. Which sets off the 8 month old because she thinks something is wrong and voila major chaos. Ive been trying to ignore the behaviour but im not sure its the way to deal with it. He is doing the same thing at home so I have to check with mom to see what they are doing about it. any advice would be appreciated.

I have a similar situation ....I started a child in feb and she was my youngest until oct when I started a 12 month old boy (she is now 18 months). If he comes near her she shreiks but if ge actually touches her or the toy she is playing she totally loses her noodle. She shoves him pushes him .... Has absolutely no tolerance for him at all. I keep telling her we must be nice or he's just looking.
It sound like your little guy might have a bit of separation anxiety or he may have laid claim on you and is showing signs of jealousy.

I find it common when the kids are new that they cry when I leave their sight, but it sounds like this little guy was already nicely settled. Given that they are all quite young, have you thougth of putting them each in a separate playpen or exersaucer when you have to leave the room for s second? Maybe it would bring a better feeling of security? Otherwise I find it just takes time before they learn that when you leave you do come back.

I also find that it is the actual opening and closing of the gate that upsets them. Even if I am just opening the gate that leads to the front door area to put something on the bench the little ones scream. Closing a door seems to have the same effect.