In the Package Manager Console write next commands:
PM> Enable-Migrations -ProjectName "MockData.Entity" -StartUpProjectName "Mockdata"
Where keys -ProjectName "project name in solution with DbContext" -StartUpProjectName "startup project"
Аfter changing the structure of the object, enter:
PM> Add-Migration AddOrderPrice -ProjectName "MockData.Entity" -StartUpProjectName "Mockdata"
PM> Update-Database -ProjectName "MockData.Entity" -StartUpProjectName "Mockdata"
Where AddOrderPrice migration name