I agree with both Bwburke94 and SOTO. I think both their positions can be implemented. Their two positions seem to be:
- We are not (cannot be) sure whether Petronella IS her name;
- Petronella is NOT her name.
But in either case Petronella should not be used in the page name.
And, if this decision is made, then SOTO's suggestion to stick to the facts is ideal. No one can argue that (1) she said her name was Petronella (I would use "said" instead of "claimed" as more neutral). It can be also said that (2) the Doctor called her Petronella after this (once?) and that (3) no one else has been known to call her Petronella. Here (1) and (2) are just facts, and (3) records the hesitation whether it is her real name by using in-universe information. (3) can be strengthened by Osgood's words from Extinction that everyone calls her Osgood (I cite from memory). So it can even be claimed that no one in UNIT addresses her by first name.
Also the in-universe/out-of-universe angle suggests putting any discussion over whether it is her actual name in the Behind-the-Scenes section, as this discussion indeed did not happen in-universe. This is how it was done, for instance, in Polly Wright.