Bring a script in, keep writing, and hand an FDX back to the office. This is what each element does on the way through — so you can check the one you care about before you move a draft.
These keep their element on the way in and on the way out. A scene heading is still a scene heading when the office opens the FDX.
Final Draft has a few paragraph types with no direct counterpart. The words come across and stay where you put them — they just read as action.
Anything Inkwell does not recognise is kept as action and flagged on the import summary, so a file from an unusual template never silently loses a page.
The script moves. The production bookkeeping wrapped around it does not — so if you are mid-production on locked pages, keep the office copy as the record of record.
Depending on either of these?Tell us before you move a draft
Two characters speaking at once come in as a pair and go back out as a pair.
Emphasis converts between Fountain markers and Final Draft styles instead of leaking asterisks into your page.
Notes in the margin survive the round trip rather than being flattened into the script body.
Import an FDX or a Fountain file on the free plan and write. Fountain and PDF export are free too; FDX export is on Writer and above, for when the office asks for it.