EPM offline mode issue

Struggling with offline mode for an input form.

Idea is that we'd take the input form offline, an individual fills it out, then sends it back and we save the data.

I first tried just taking it offline, but the cells I need them to fill in are locked.

I then tried checking the below boxes to keep them unlocked, which worked, but as soon as I turned the file back online, it give me a message box saying "You can't undo deleting sheets, and you might be removing some data. If you don't need it, click Delete". So it appears the delete the "offline copy" of that worksheet and all the inputs are deleted and the worksheet is reverted back to it's original state.

Note that the cells I'm looking to have them update are cells that are excel formula's grabbing information from EPM reports in the same worksheet. There is then another 'input form' in the worksheet that feeds from the cells that are updated.

Thanks in advance.