I think if you convert ownership of 529 to your D, It falls under Untaxed income. I think the formula for student t income(taxes and untaxed) gives the kid $9k allowance before adding half the excess directly onto EFC.
If OP lends Daughter $X in loans for college, then takes PLUS to get those funds he’s lending.her, I don’t see a problem. Loan has to have paperwork generated and signed, exactly as any loan needs to be executed with payback terms. And market interest rate. Payment of interest annually by daughter should be i. There and at today’s rates no hardship. I know someone who did this— kid wanted to go to a pricier college than there were funds, and so parent took out the PLUS with loan contract with kid because those private loans hamstringing kid and parent are more draconian in terms and show up on credit reports. Parent forgave the loans upon graduation, which he may not have done if kid didn’t finish college.
In this case, some of 529 can be used to repay the loan—up to $10k, if evoked before last year, use won’t affect FAFSA