My concern is if we only had a single company, then the transaction would be Dr Fixed Asset and Cr Revaluation reserve

By "moving" the asset in this way we are recognising what would otherwise be a revaluation through the P&L. Both subsidiaries are 100% owned by the same parent.

I agree on the consolidated position, its the presentation in the subsidiaries that concerns me.

There are plenty of hacking/cracking programs easily available on the internet which allows their users to read the password and hence break into files. These sorts of password are useful to prevent the casual reader from opening, but unfortunately are very easy to overcome.

To be more secure there are encryptions programs such as PGP key based ones, these are very much harder to break but potentially breakable also..