Firstly, vermicompost generated from dog manure is not safe to use on edible plants due to possible pathogens. It's OK to use it on ornamental plants.
Secondly, please do not assume that worm compost contain worm cocoons. If any, then possibly just a few. If the vermicompost is processed long enough that all material has been composted and cured that is.
Unless you find a worm farmer who is in a hurry to sell his "black gold", then you might find cocoons and babies and even a few worms that haven't moved along. Since you won't know how many worms you'll start with, you might be waiting for a very long time until the dog pile get processed.
So, adding worm castings to your dog manure pile might not work. Sorry.