quick FBAR question

In a related question, does my UKC partner (we're not married) who I (a USC) share one joint account with in the UK need to sign the form?  It seems that she might have to, but she is not a US Person by any stretch. When listing the account details, it asks for the name of the principal joint holder, which I consider me, as most of the money going in is from my wages.  The instructions also say that if the joint holder is a spouse they need to sign Section III, although I see no place to sign on Section III.  Anyway, she's not my spouse so does she not have to sign?

Frankly, I greatly distrust governments in general, and I'd rather not give them any more information than is required by law, even the name and signature of my partner.  As far as I'm concerned, it's none of their business as she has no ties whatsoever to the US (besides me and our dual citizen baby girl). 

The IRS has no jurisdiction over your partner unless they're required to file a US tax return. Regardless of the IRS's instructions, I wouldn't sign such a form as a partner.

Much of what they say is frequently nonsense; but if you do not know you should ask in writing so that you have evidence if you are later penalised.

A very wise precaution. The following is the last paragraph from page 95 of the 1040 instructions:

"By law, you are responsible for paying your share of federal income tax. If we should make an error in answering your question, you are still responsible for the payment of the correct tax. Should this occur, however, you will not be charged any penalty."
(What isn't mentioned is late interest payments, which may also be included.)

Unfortunately, I've found that the IRS at times responds to letters with a phone call. Since the IRS admits that it is possible to make an error, I would prefer to have a record of that error in writing. If you feel comfortable with just a phone conversation, be sure to record all dates and times, the advisers name, and his ID number (in the past, they would give their ID number. I don't know if they still do). Then write down your complete recollection of the conversation, and information given, immediately after hanging up. But if it comes to justification, the strongest evidence is IRS headed stationary.

The IRS has no jurisdiction over your partner unless they're required to file a US tax return. Regardless of the IRS's instructions, I wouldn't sign such a form as a partner.

The person signing it should be the one filing the form.  If you have to report your partner's stuff because they are a joint holder, that doesn't then make them liable to sign the form.