Many people who find raising sheep fascinating are also interested in other livestock species such as llamas, alpacas, and goats.
Raising sheep is a very popular activity in smaller scale farming operations and other ruminant animals often compliment and add to the diversity of the flock and farm.
A good way to decipher the how tos' of other animals and plan for them is to begin with some research.
From a management perspective there are advantages and disadvantages of raising livestock together depending on the type of livestock and the management style of the farm operation.
For example sheep and goats do share some diseases making some leery of raising the two together while others turn this to their advantage and successfully raise the two together.
Each one of these points may prove to be advantageous or disadvantageous depending on your philosophies of raising sheep, the included animals and how you manage your farm operations.
Disease and Health of animals - do the animals share common diseases
Predator control - some livestock are a greater deterrent to predators
Parasite management - other livestock can aid in pasture clean up of parasites if they are not prone to being burdened by similar parasites
Foraging diversity - different livestock prefer eating different forages
Pasture management via stock density - up to a point, running all stock together can increase utilization of a pasture without added strain on the grasses
Treatment of Animals - running animals together means seperating them for needed treatments
Handling systems - larger livestock will require separate handling systems than smaller livestock
Fencing - your fence will need to be secure enough for the species most likely to test it
Mineral programs - separate free choice minerals can alleviate this issue however planning and good land management practices will be needed
Breeding times - may require separation and management around breeding
Sheep are highly adaptable and their generally meek personalities pave the way for acceptance of other animals readily.
Provided there is a settle in and get to know you process other livestock animals can be introduced to and raised right with the flock.