Not an unusual occurrence. But assuming there is no "business of real estate" the first question is what does "invested in a building" have to do with "selling the house"?

Second, every partner "made" 29,000. What does "made" mean?  Is that cash flow which is irrelvant to the taxation of is it net profit?

If the 1099-S was only in your client's SSN then you need to show the sales price reflective of that. Otherwise the IRS matching program will send a letter saying we have this and you show that.

What I do in the 8949 description is to report 33.333% ownership in 123 Main St..., proper purchase date, proper sale date. In the sales price column I put the entire contract price to match the 1099-S.  In the cost basis column I create a supporting schedule showing purchase price, purchase capitalizeable settlement costs, improvements, sale settlement costs and then a line to net out the other 2/3 ownership. In this example and assuming no other costs I would have $300,000 SP, $271,000 cost for a net profit of $29,000.