If the price of an equity forward contract with multi period dividends is calculated as x for 150 days and then you have to value it at 70 days, would you not just discount x with rfr for 80 days ?
As long as you use the correct risk-free rate: the 80-day risk-free rate starting 70 days from today.
If I’m reading your question correctly.
Yes. I thought discounting would appropriately take care of the interim dividends as that was accounted for in the original forward price.
But in the answer they have just calculated a new forward price at time t. (And the dividends make it cumbersome)