Hi Helen - please mail me at pdelange@doc.govt.nz. I got your parcel today
"randomly along the track' = Kunzea robusta as the branchlets hairs are antrorse, appressed and mostly long and silky, the 'fruits' are 4-5-locular and broadly turbinate
'Specimens taken from the kanuka in the photos' - look rather like Kunzea serotina x K. robusta - the branchlet hairs are mostly minute and divergent (i.e. stick out from the stem at 90 degrees = K. serotina) but there are mixtures of these and long, appressed, antrorse hairs (= K.robusta), some pherophylls are spathulate (= K. serotina), the 'fruits' are (4-)5- locular (= K. robusta)
The Pimelea is probably something in the P. oreophila complex - I dislike Pimelea, the current treatment is a complete mess and I can't work with your sample - its too small.
Hope that helps. Ciao Peter