Not questioning the settlement per se, but rather if there is something IN the settlement where, for example, his larger share of investments was designated as because she was getting the house. If there is wording specifically stating the house as his reason for getting more investments, that could be a de facto purchase of his part of the house, increasing her basis.
TIA to all for answers; I'm just going to tell her she gets to exclude $250k, their joint basis from purchase, plus any major upgrades done while they/she owned the house.