Hi there,
* You can export the product (or products) into a CSV file, then edit the spreadsheet (to add the variants) in bulk. There are many CSV import/export plugins, or you can use the built-in import/export tool at Products > import/export.
* You can also put the simple product (or products) to Draft mode, then create a new variable product.
Let us know if there are any questions.
Precisely I had a query with variable Subscriptions (It MAY apply to other product types as well). After sitting on this matter for two full days and trying all possible solutions I came to know that Once created you change Edit product type (in my case variable Subscriptions) unless you delete all the existing Subscriptions First. So if I wanted to change product type from variable to simple or vice versa you would not be able to do that unless you delete all existing subscriptions first. Those subscriptions must not even be there in trash. Only then will you be able to edit the product type.
Thanks for your reply Igor
This resolves the issue – posted here to help anyone else who would want to do this and there is no mention of this anywhere else I searched in the entire documentation. I deactivated all subscriptions and deleted them and then even from trash. I could only then change the product type of subscription from simple to variable etc. This becomes necessary when we are testing the software before moving it to live
Thanks
@arvindve
Glad to hear it – thanks for letting us know!
If you have any further questions, I recommend creating a new thread.