Thanks for the kind comments. When my wife mentioned she wondered how many full skirts there are, that was the only excuse I needed to start collecting them! I presented the collection to her as a Christmas present last year (it has taken me that long to finish the report... Delayed by the 2016 releases and the 'discovery' of the Quick figures).
Tiermann: thanks for those links, which helped confirm my collection is reasonably complete; Playmo-family has an additional light pink child's skirt but hasn't included the one from 6626. What I found most interesting was that Klickywelt contributors appear to have the facility to add to a post indefinitely, so Playmo-Family has added more pictures (most recently in March 2016) to her first post (in May 2008) as new skirts have been issued.
StJohn: I originally (and Anglocentrically) thought reifrocke was a compound of rei and frock (frock being a rather antiquated word in English for a dress or skirt, as I am sure you know). But it's likely a compound of reif and rock. Reif translates as ripe or full, but reifen or hoop sounds plausible too.