If the holding of the purchased land is short-term, meaning held for less than a year, you can break this down into two separate sales, since the inherited land will have a long-term holding period.
If it's all long term, you can just use the method as purchased and choose various as the date acquired, then you will choose that it's all long-term. The only point of using inherited is to establish that it's a long-term holding, which is true or all inherited assets, regardless of the date inherited.
If the holding of the purchased land is short-term, meaning held for less than a year, you can break this down into two separate sales, since the inherited land will have a long-term holding period.
If it's all long term, you can just use the method as purchased and choose various as the date acquired, then you will choose that it's all long-term. The only point of using inherited is to establish that it's a long-term holding, which is true or all inherited assets, regardless of the date inherited.
It is Long Term Holdings: Inherited 6 acres in 2004 and then Purchased 3 additional acres of same land parcel in 2008 from a joint owner
Good, having all the land be long-term holdings makes it much simpler. Still, if you prefer, you can break it down into 2 transactions, one with a basis of inherited and one purchased, and just allocate the proceeds from the sale by 2/3 and 1/3. Either way will do.