Macbre but perhaps practical method for brother to provide his trustworthy older sister (her income limited to Social Security) with extra annual income until her death in an amount equal to the substantial equity in her mortgage free home- her only asset, i.e., brother makes annual tax free gifts to her and she bequeaths her home to him. Sister's trustworthy children would document not to contest such bequeathment and trustworthy uncle would make equal annual tax free gifts to them amounting to his net from subsequent house sale, less the sum of his prior gifts to sister, ignoring interest.

If above practical, I assume the sister's $ 250,000 exemption on sale of her primary residence would end upon her death. If so, upon subsequent sale by brother, would his heavily taxed basis be that of deceased sister or could it be the much higher FMV as determine by an independant appraisal immediately after death? .