Those are wonderful pictures of Jack. Thank you for sharing them with us.

I had not heard of keeping a journal, but I think it's a great idea.
When our Cocker passed Bruce made a memorial slideshow including pictures and video. There are some creative people here on PT, maybe someone would be willing to do that for Kate...? I would, but I'm not so creative.
Also, when my brothers dog died I made a collage frame of pictures like Meg mentions above for the family.
We also have DJ's (the cocker) remains on a shelf along with a couple pictures of him, two of his collars and his favorite toy.

I hope you can find comfort in writing in the journal to Jack. Please give some loving to Sunny for me.