Thank you, I will give that a shot.
Certainly worth asking, but don't be surprised if the answer's no. I don't know what your previous upload device was, but the data may well be held at weatherlink.com in a distinct format from the one that WLL uploads use. So while almost all data transformations are possible in principle, it may not be viable for Davis to do in practice (at least currently).
The only definite way I know of for getting old data into a new WLL station is to create a single
local text file of data that uses exactly the same format as exports from the Browse menu of Weatherlink for Windows. There is then an upload feature for such files. But this
must be done carefully - any significant errors in the upload file may be tricky to recover from. If you have old data in Weatherlink for Windows files
and follow the instructions carefully then all should work OK, but that's probably the only reliable option.