I too am so sorry to hear of your dad's passing, please accept my condolences also.
Jackie is right, you and Prissy have had a lot to bear of late, more than most people that's for sure.
Dogs, in fact all animals grieve, just as we do. It's natural and healthy, but I always do as Jackie does, talk to my animals, because I too believe that on some level they do understand us, more than we realize. Prissy will definitely feel his loss, very much so, as she's been with him so much, he's been a part of her world. And I am willing to bet, helped her with her problems too.
Jackie has given you grand advice, there's not really anything I can add, except that my late cat Buddha grieved for quite a long time when he lost his best friend, my late German Shepherd Jacques. He, like Jackie's dog, just appeared long enough to do his potty, then returned to his 'secret' place to grieve. It took a while, but he did come through it, and even 'trained' the two puppies who arrived home a few weeks later.
And I'll also second Jackie, be good to yourself, you're also grieving and have had a really tough time. Take care of yourselves and yes, never forget, you've got friends here if you need a shoulder, we're always here and always ready to help.
Take care Prissy and Kim, my thoughts are with you both.