Oooops, the answer is actually “yes” , but the process is not practical. There was a post at Yahoo in 2011. I believe the builder that was mentioned was Rick Rubarth who now builds and sells RHarps.
There was also the harp made in England (Morley?) with 43 strings, I think, that could have a pedal mechanism added. That was fairly recent.
I may be wrong, although I just read the Yahoo reference so it can be googled.
I’m not absolutely sure, so I’d rather say “maybe” than “No”.