I don't have a better memory nor access to my pony collection, but in general when it's a HK and China thing, the HK ones more often show up stateside and the Chinese ones in Europe. That is absolutely not a set rule, just a guideline.
In the UK for sure we had the US sets sold as three (mum, baby, dad) and they were in US boxes. I think we tracked them down to Woolworths. I have a box for the Apple Delight set (actually, Nella, its the exact box for the ponies you bought from me, so their provenance is American!) and I think it says something about HK on it, but I think the ponies I sold you were Chinese? If so it's really not a set rule...
We also had them sold separately on cards. I know that the NC adults come from that separated set. I've not seen a HK baby for the exclusive three ponies, but I haven't spent a lot of time looking at the others. I think most of the ones I've seen have been Chinese, but as I said, since the UK had US imports and our own European release, I don't know if that is significant.
All I know is that I have never seen a HK adult from this country. I also don't think I have a single HK adult for the families in my collection. Only NC and Chinese...