Can I redo my HDB HFE before applying the HDB loan and get more grant?

Let's say both me and spouse applied HFE, booked a flat, paid deposit.

So before the final stage of loan application, if both of us retrenched and then took a slightly lower salary, can we redo the HFE to lock in our new incomes and get more grant as our combined income dropped?

or is everything locked at the stage of booking flat after ballots?