[fish hawk]

I think you are right. I believe some Polynesians made it to South American and came north, making three ports of entry.

[wolfcreek]

And when you consider the moving continents, groups may have been separated or join throughout history.

[tbw2]

Yams (sweet potatos) are native to south america. There had to be colonization at some point in order for Polynesians to have picked up sweet potatos. It isn’t quite like fruit where you plant it, watch the tree pop up, and remember the fruit. You’d need to get cuttings/roots to plant to propogate it, which would take more than a food raid on the coast to get.