var context1=new MyContext();
var context2=new MyContext();
var entity1=context1.Entities1.First();
entity1.Field1=5;
context2.SaveChanges();
context2.Entry(entity1).State = EntityState.Modified;
context2.SaveChanges();
var result = context.Users.Include(...).Where(...);
foreach(User u in result)
{
u.Name="Domain\\"+Name;
}
await context.SaveChangesAsync();