1.5yr old starting to get aggressive

She is taking it out possibly on other kid as well.. they have emotions and NO , yelled at any one isn't kind to hear especially with the baby who is her sibling? My husband used say no a lot or don't do this or that, mine just turned 4 and 5 but the tone of no, is aggressive, even if we think it isn't and they need to hear it. I used to take their hands and pet her and say, she too small to play and she has to grow. Gentle and put my hand on theirs and pet baby body, and then pet baby myself, gives them how to interact... I would say uh ah , like nah uh, as in don't do that... they were times I was short fuse and youngest would pat baby on head and she cry and my 5yr old told me. . However new baby, high emotion, lack sleep... my husband was more unkind in his method. I have more compassion and he was short fused.. even though it new baby and I'm home all day, no help. It is , jealous in a way, could be everyone is more high strung around her and everyone so happy with baby, they see it

Ps lot of hugs help, redirect and play with her. She looking maybe to touch baby, but we see it as hitting... but because she tried so many times, getting yelled at, she upset.. sad I see it happen. I let my littles hold baby and my mum was shocked. I never knew it was easy, put pillow under and let them hold, interact... everyone wants safety and keep away etc, but 1.5 is really really small... Mine was newborn and his brother was 1 year 4 months, he didn't hit.... he gave hugs every now then, patted etc... but no one was shouting as much 3rd pregnancy and then she came... it happens