Adding a false nominee income means you are filing a false tax return.
That's a no-no.
Why do you say he's a 'false' nominee. He is the owner of the stock, He is the source of the funds used to buy the stock. Schwab doesn't allow a split reporting of income.
prepare the tax return both ways, with and without his sell transactions.
have him write you a check for the difference when you file correctly according to your consolidated1099-B.
If he doesn't like your capital gains tax rate, he should have his own brokerage account.
I found the answer. If you import your tcapital gains info directly from the institution it doesn't allow this, But if you enter you capital gains manually there is a checkbox for Adjustments to Proceeds, or something like that. This is where you put the code for wash sales (W) etc. One of the codes is 'N' - nominee. There you can deduct the amount that is not yours. For Div and Int you need to send the person a 10099-DIV or 1099-INT, unless if it's your spouse. I'm not sure if the same is true for capital gains.