Still not too clear on this one.
Well, apparently that makes two of us

. As I have said from the beginning, if I could know the actual musical text, that would be pretty helpful. It's not actually *all* that much to go on by what you are describing, since in my mind, there could be more to it that you aren't seeing or that is not quite being communicated.
I am back to my original question on the Ab major chord identification. With the secondary dominant idea, it would actually be a V 65 of V.
It's fine for the secondary V to be inverted.
Now you suggest it might then resolve to a V (of Eb).
The whole point of raising the third of the chord in the secondary dominant, from Db to D natural, is to provide a leading tone to the root of the chord it is preparing ... in this case, it would be Eb.
The actual note Eb is not in that second chord, would you assume that the Eb note would not need to be there but would be 'understood'.
Well, I don't like to be "assuming" anything here

. Sometimes a specific chord will harmonically function in an area of the phrase that is not specific to it's individual name. For example, both the V chord and vii dim chord (can) function in a dominant context, though the diminished chord is not called the "dominant" chord (it's rather a dominant substitute), but the
function is that of preparing for tonic.
In most cases, to name a triad/chord, you need at least the root and, to have the quality of the chord be clear, the third. If the root is not there but there are other tones, then it is most likely not the chord you think it should be (I'm sure there are exceptions though -- but unless you are doing a test from what would be considered second year theory or beyond, then I don't think this is the exception).
Does a V7/V have to be followed by a V chord?
There are exceptions, where secondary preparation chords do not lead to the chord they prepare, but I am doubting that this is meant as an example of that.
Conversely if I were to go with the ii 65 #3 followed by vii 64 is this an acceptable progression. The I chord precedes these two chords and also ends with I.
Well, from where my perspective is at the time, I would say no. However, I am basing my responses to you on a basic phrase model, where most of the time a cadence that ends in a tonic chord is preceded by a dominant area functioning chord (either V or vii). Perhaps somebody else can be of more assistance to you.