Form: Send form, review and make some operations with data, resend form

Hello,

I'm quite a newbie with Nette and I would like to ask for help with the following (maybe simple) problem:

1.) I have form that contains only one textarea.
2.) User can write to that textarea, one value per line.
3.) After form submission I would like to show entered values to the user as checkbox (one line = one checkbox) and allow user to check values that would be stored in the database.
4.) Send the (second) form and store data.

I have no idea how to proceed with the (double) form submission. (I have already implemented the part with DB and regular form and it works great).

Thank you very much!

Jakub