Be aware that structuring a transaction to avoid the mandatory bank reporting rules for transfers over $10,000 can sometimes constitute a separate crime called "structuring", even if the underlying purpose of the transaction is totally legal.
From an income tax point of view, there is nothing problematic about being paid back a personal loan from a family member in any amount. However, when you make a loan, you are required to report the interest you charge as taxable income. Even if you don't charge interest, you are required to report and pay tax on the interest you could have charged, using at least the applicable federal minimum interest rate. This is called imputed interest, and there is a blog post about it here.
https://turbotax.intuit.com/tax-tips/tax-payments/irs-tax-rules-for-imputed-interest/L7UbulHpC
So from a tax point of view, there is nothing wrong with making large money transfers, but if you are audited, the IRS may want to see proof this was a loan (documents or some kind of agreement) and you may be required to report and pay tax on the imputed interest. From a money laundering point of view, I would avoid "structuring" the repayment to avoid the banking regulations.
