There isn't a direct way to upload/import a watch list; Here's something that you can try.
1. In Excel have all your Watchlist in one column and add a comma at the end of each one ticker
2. select the entire column and copy it
3. Open your portfolio or create a new one, go to '+ Add Symbol' , paste the selection and hit 'Done'
Your desired watchlist tickers will be added to your desired portfolio.
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