From a composting point of view, it is not a problem to compost crumbled dog poo together with grass clippings. In fact, it should work reasonably well, seeing the dog poo is crumbled into small pieces and mixed with grass clippings. The issue however is that backyard composting is not able to adequately eliminate pathogens, parasites and weed seeds, as small volume backyard composting fails to generate temperatures above 55 C for prolonged periods, which is necessary for pathogen and parasite elimination. Therefore, the composting of animal droppings in small backyard composting systems carries an inherent pathogen / parasite infection risk, particularly when the finished compost is handled and spread around the garden or used for pot plants, and is not recommended. For the above stated reasons we also recommend not to compost dog poo in backyard systems, as we do not want our customers exposed to unnecessary risks.
If you want to make best use of dog poo in your own garden, you can dig holes and bury it in the soil. To aid this process, you can use a product called SHIFT.