I'm really sorry for your loss, it must have been hard for you.
My personal experience is as follows. When I had to get my beloved Bumper, euthanased, I was very concerned about the other cats, as they were all very close. I had him done here at home, and kept him afterwards for a few hours to allow the others to see & smell his body, I guess I just didn't want them to think he had just disappeared. They all came down to smell him, but I must admit I was a little surprised by how 'unbothered' the cats seemed by it all. I came to the conclusion that maybe I was just putting human emotions and qualities onto them. However, I have no idea if it would have been different if I hadn't let them see his body - maybe they would have become depressed at the absence of their big brother. In the following weeks, they did seem to look for Bumper in his usual spots, and seemed a little confused as to why he wasn't there, but as far as I could tell, they got over it a lot quicker than I did. I don't know what they were thinking or feeling, but they never seemed to have any visible changes in behaviour or temperament that I would associate with grieving, other than the seldom searching for Bumper.
One of my dogs, on the other hand, took it far worse, and became depressed and upset. Again, this is a situation I didn't fully understand. Asha was close to Bumper, and was nervous of his body when introduced to it. Was she grieving him afterwards, or was she literally just picking up on and acting on my own grief, depression and sadness? Dogs have been known to mimic their owners moods. I guess it's something I will never fully understand, but I did find a lot of comfort in them still being there.
Please take care, love and cherish your little girl, and one day maybe you will feel you can offer some of your love to another kitty in need.