This question is whether or not a taildragger-'rating' authorised by the foreign authorities is possible if you do not have that very same specification on your original licence.
Apart from taildragger not being a "rating" (as described above), the general consensus is that it's a bad idea to start piling additional endorsements, rating and whatnot onto a "piggyback" certificate.
The reason is that you're building a house of cards, that will come tumbling down if one of the base cards crumbles.
As an example which might not be too ficticious: Your FAA piggyback PPL is tied to a JAA license with a specific number. If EASA gets its wish and your UK-issued JAA license is replaced with an EASA license, the license number might change. This will not only invalidate the FAA piggyback PPL, but also anything that you added to it.
So if you want to add anything to an FAA PPL, get a standalone one. Use the piggyback only for a flying holiday.
What are the three types?
- The "arrival"
- The "good landing": The one you can walk away from
- The "great landing": The one that lets you use the plane again afterwards