TurboTax does not support multiple disasters on Form 8915-F, although the form itself does. To manually enter two disasters on Form 8915-F, you would need to use TurboTax for Desktop (any version). Print the form, complete it manually, and file your return by mail.
See this post for more help: How do I switch from TurboTax Online to the TurboTax software?
Also, contact TurboTax Support and request a free download due to the online program restrictions.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
