Hey all. Looking for some feedback on a particular situation and how to handle it.

I have a new client who likes to play the slots. But she keeps no records of her daily net wins and losses. She has 5 W-2Gs totalling about $10k. Then she has a printout from the casino showing about $300k  in "Slot Wager" and -$40k in "Slot Loss." Basicaly the Casino gave her the total amount she wagered and then her net loss for the year. She has nothing reporting the amount she won.

My assumption is I should take the total slot wagers, subtract the amount of loss, and that would be the total wins (300k-40k= 260k) and then back out the 10k reported on the W-2Gs (added back in by the system after entering them spartately). Then report the 260k as a loss on Schedule A. Does that sound logical or am I missing something? 

The previous guy for 2023 did something weird. He reported 300k on Schedule 1, Subtracted it on Schedule A, and then on the 1040, took the standard deduction and ignored the schedule 1. He only added in to income the few thousand that had been on the W-2Gs. He printed off the Sch 1 and the Sch A showing the large wins and losses, attached them to the tax return copies he gave her, but they were not actually used on the 1040.