public void Add(Owner newModel)
{
_ctx.Attach(newModel).State = EntityState.Added;
_ctx.SaveChanges();
}
public void Add(Pet newModel)
{
_ctx.Attach(newModel).State = EntityState.Added;
_ctx.Entry(newModel).Collection(o => o.PreviousOwner).IsModified = true;
_ctx.SaveChanges();
}