How can other time lords, post time-war, drive/fly a TARDIS?

Question

Two parts allow time lords to fly through time and space, in TARDII (?):

1. When a Gallifreyan was granted the rank of Junior Time Lord in the Time Lord Academy, they received their symbiotic nuclei. (PROSE: Interference - Book One)
2. The Sixth Doctor once claimed that TARDISes (or other time machines) had to be primed with a Rassilon Imprimatur to enabled them to travel safely in time.(TV: The Two Doctors)

_{~Rassilon Imprimatur}

Now, no one is making more TARDISes, but we've seen a few new time-lords...in the loosest sense:

1. Donna-Doctor
2. The Doctors Clone/Daughter
3. River Song

Now, we haven't seen all of these fly the TARDIS, we've do it with the Doctor, but that's cheating.

Do these/would/should these have the same ability to fly the TARDIS? If not, what's the limitation on flying one without the symbiotic nuclei? Has anyone managed that?

Answer 1

We have only actually seen one person fly a TARDIS, on their own, without The Doctor being involved, and that's River Song. (Donna flew it in conjunction with The Clone Doctor, I think.)

In general your intuition seems to be correct that we shouldn't be seeing anyone else new being able to pilot the TARDIS. Eleven seems stunned when River demonstrates an aptitude for piloting his TARDIS, and claims it ought to be impossible. In River's case, she explains in Let's Kill Hitler how she was able to do it - the TARDIS let her. When she pilots the TARDIS to where The Doctor is dying of poison, she explains to everyone that "she [the TARDIS] taught me how to fly her."

In general, in the post Time-War era, the individuality and personality of the TARDIS has been something brought much more to the forefront. Remember she is the last TARDIS as much as he is the last Doctor. It seems as if the "rules" surrounding TARDIS flight in the age of the Time Lords are only conventions or guidelines that everyone followed, and not anything that is inherent to the nature of a TARDIS.

So, in theory, a TARDIS could permit anyone they wanted to fly them, and teach them how, but so far, of all the people that have been in the TARDIS post-Time War, only one (a very unique one) has actually been able to do so.

Answer 2

In the earlier ones Season 19 for example, there is a companion "adric" who managed to fly the Tardis several times alone.

Answer 3

We have seen in much earlier series both the Master and Rani fly a TARDIS. I think Romana also bit in some episodes it became clear the Romana and Rani where the same woman. Also went to school with the Doctor. She also helped the Doctor on occasion instead of the Master.