Years ago I lived with my sister and we had 4 female cats. My first cat was the dominant without having to fight for it. One of our chairs in the living room was Kittie's. If one of the others was on it when Kittie walked into the room she would jump down and Kittie would sit in it. Sometimes she would allow one of the other cats to sit with her, but it was her chair.
The evening after putting Kittie to sleep, all 3 sat by the chair staring at it. It went on for about an hour. Out of nowhere I said "Kittie, it's OK to go. I will always love you." After saying that, the 3 of them jumped into the chair and cuddled with each other.
I had another instance as well.
My Grandfather passed away when I was in high school. I was already in bed when my parents came home. They came into my room to tell me. I cried and my dad sat with me for some time. After he left I tried to fall back to sleep, but my bed's headboard kept tapping the wall. (My bed was an antique with a 6' headboard.) I initially thought it's me, I must be shaking from crying so I laid still, but the tapping continued. Again, out of nowhere I said, "grandpa, please stop". It stopped.
I believe in Heaven and know they are there and will one day see them again,