Thanks SoHopeful. For my wife's visa application we are completing Appendix 2 just to be safe of course. Doesn't hurt to complete the form anyway. I've also completed the sponsorship undertaking form, even though it is only supposed to be for Adult Dependent relatives.
As far as I understand things though, the UKBA no longer exists. Hasn't it been absorbed into the Home Office now?
VFS seemed to be the only people who could advise on the specifics of the online application process though? Now that HGS are handling all the queries all we get is a cursory link to a page on the gov.uk website. Both times we have contacted HGS this has been the case, and both times the page they sent us to has been completely irrelevant to our application.
If the information we were after was on the website we wouldn't have emailed them to ask, and the least they could do is send us links to the correct pages for our category of visa! Very frustrating.