OK first congratulations on the winnings.
The $10K you gave the daughter and granddaughter are not deductible.
You report the W-2G as you got it.
Then if you sold it outright to an unrelated party at highest price you could get for it, you can make a deduction for the difference on this. You would enter a negative amount of line 21 "Other income." You do this by going to Wages and Income and all the way to the Bottom to Misc Income. then to bottom again and it would go here.
