One furry companion, whether pet or service animal, does not interchange with another. They are all individuals.

My third daughter died as a baby. The fact that I have two other daughters who are now grown does not diminish the fact that I still grieve for Jessica, and it will be 22 years tomorrow.

Good heavens, I just realized why I feel so gloomy today. My condolences to you in your loss, since I share your feelings. Animals are not the same as children, but they are dear too.