Hiya
I think it is the cutest and most wonderful thing that you are worried about your little one, but i wouldn't fret too much.
I grew up with my family dog, Cisco, a shihtzu-poo. He slept with me growing up and I took care of him a lot as well (not your typical kid who doesn't feed or walk the dog lol. When I went to Los angeles for school and had to leave cisco behind and my mother and father got divorced so my mom just had cisco, so who was I to take from her? So long story short, cisco is just fine. Does he miss me? Yes he does and he comes to visit me some times and acts like he is on vacation. One poster said that they adjust to your energy levels, this is very true. With my mom and step dad he is very calm and lazy. He comes to my house he is super playful and just like a puppy again! He is 15 now!!
So I wouldn't worry, because that energy could make him feel uneasy, he is HAPPY to have YOU and happy when he sees your kids again!
Regarding your father ... Charlie may have felt it was his time to go or maybe felt his pain? Dogs have known to be sensitive to things like that and maybe it was just too much for him to bear.