If you were entitled to a 1/7th share, then technically you should only report 1/7th of the selling price and 1/7th of the cost basis. The cost basis is the fair market value on the date your mother died. Assuming you sold the home fairly close in time to when she died, this means your cost basis is the same as the selling price and you won't have any taxable capital gain income, even though you need to report it.
The problem is that if you only report your share of the selling price (1/7th in this case), but the 1099-S is for the entire amount, the IRS will probably send a letter of inquiry. One solution is to only report 1/7th the price and 17th the basis, but file by mail instead of e-filing, and include a copy of the 1099-S and a written explanation attached to the tax return. If you want to e-file, the solution suggested by the other expert is to use a higher cost basis so the gain comes out the same.
