S.H.
very 1st thought was already posted by Michelle. It is truly a hardship for the older dog. Puppyhood is extremely wearing on the older dog.
& the fact that you are allowing the pup to be an inside/outside dog will create issues. The old dog will want to join the family, too.
Been there, lived all of this....& regretted it deeply.
As for collies, I've known both temperaments. Depends on the breed lines & how the pup is raised.