There are two different ways that a property can be held jointly: Tenants in Common or Joint Tenants?
If you co-own a property as tenants in common, each co-owner owns a specific share of the property. As you each own a separate share in the property you are all entitled to leave your individual share to your chosen beneficiaries in your Will.
When you co-own a property as joint tenants, each co-owner owns the whole of the property and neither owner has a specific or identifiable share. When you die, the surviving co-owners will automatically own the whole of the property, regardless of any wishes you may have made in your Will regarding the property.