Otto the little buttface, meet Sir Otto Big Head extraordinaire.
I had to laugh because they have the same name and Otto was such a little twerp. He's still a boss dog but he's stopped chewing on children.
Get a leash for the cat work. Cats will do what they want, I have one of those too and she's a piece of work, all 6.6 lbs of her thinking she's going to beat up a german shepherd. If Otto's not biting the cat, they'll work it out. My 14 month old loves to chase the cat. When she catches the cat, she just licks her. If Otto's not doing THAT, you need to just step on the leash and say NO firmly. Sometimes time out and shaming works.
Little times out for being bad puppy. Sometimes they're just bad because they're ramped up and need a nap. I used to put my Otto in the kitchen for TO and come back 5 minutes later to him sound asleep. You have a human toddler, you know the tired tirade.
Just NO to tackling the baby. TO and shame.
Get Dad and the 5 year old a couple boodah tugs so they can interact in a positive way with the pup (you have to let them win). If you don't have any booda tugs, cut up a piece of fleece blanket. 3 strips of fleece about 2 ft long and braid it together with knots on the ends. Perfect tug.