Cost basis on discounted property

[Chris L.]

If you did a partial sale/partial gift purchase of a business from your parent and the purchased and gifted portions were discounted( lack of marketability and lack or control discounts)..... If you paid 350k for 51% of the business and this amount was based on the “discounted value” how would you determine cost basis? Would the portion you purchased have a cost basis of 350k OR would the 51% purchased have a cost basis based on the value prior to discounts?   For the portion you were gifted, would the cost basis be your parents original cost basis?

Any input would be appreciated. Thank you