Lock Cells To Prevent Predefined Range Macro Copying

I have a spreadsheet that allows users to paste set data from a PDF Image (using OCR) straight into Excel and then use the MID function to split the data accordingly.

Unfortunately, the OCR isn’t too intuitive and gets it wrong sometimes.

So to counter this, in another sheet (in the same workbook) I have a manual input section, and a simple macro button that pastes this data into the same fields where the OCR text would be, so that the main sheet works exactly the same way as before.

The problem is, and most likely due to the simplicity of the sheet, if a combination of OCR pasting and manual inputting is used, when I hit the paste button, it over rides the OCR data with blank cells

In the link below I have shown what is currently happening (1, 2, 3), and an example of what I would actually like it to do (4, 5, 6).

Example - Online Spreadsheets - EditGrid

So, in the 2nd scenario, I would like “5” to recognise that the respective cells in “4” already contain data and fill them ‘Grey’. This I have already achieved with basic conditional formatting.

However, I need to take it 1 step further and say that if the parent sheets cell (Auto OCR) contains data, as well as filling cells (in sheet Manual) lock these cells off and prevent the end user from adding data and/ or being copied over to the parent sheet.

Is this possible?

The result then being the parent sheet with both OCR text and copied text from the manual input sheet.

Both sheets are protected anyway and only allow for user input in certain areas, so is it even possible to apply further protection once the sheet is locked already?