father sold son 50% undivided interest in property:   house, farm buildings, 80 acres

I'm doing both father and son's tax returns.   I have questions concerning both returns.

1) for father - do I report sale using 50% of the farm buildings/land cost or do I leave his cost as is and just report a capital gain sale of "50% undivided interest" without a cost basis

2) for son -   do I enter the cost as the 100% value determined in the purchase agreement then                depreciate as 50%   or  list the 50% of farm buildings value as the cost

Am I overthinking this......          Thanks for any help you have to offer        I don't think this is in Pub17