Dont know what SACS is, but we do lift analysis using typical frame software. We model the diagonally opposite attached to two coincident nodes. One of these nodes is fixed in three degrees of translation, the second is free to translate in the vertical direction. A load equal to 25% of the total weight is then applied to the node free to translate in the opposite direction to gravity. This forces the remaining 75% onto the other slings.
Apply a temperture load to the sling member to elongate the sling. Then check the sling tension loads and iterate the temperature loads as needed to get the sling loads to the desired percentage of gravity load.
