I have used the Scrip function to add new units bought with the re-invested dividends.
However, in the portfolio summary under header “Div”, i could still see the dividend amount and this is somewhat overstating the P&L.
What should I do to prevent this?
I do not think it is overstated in my opinion because
You did receive the dividends.
Whether you used that dividends to buy stocks or not should not affect P&L + Div for that stock.
(Note: This is provided that you are not stating that you are paying 0 dollar for the scrip shares)