Currently, it is possible to perform just only 1 load combination using Delta effects (one stiffness matrix per structure), and as far as the comments by technical support of SACS, this is the way in which SACS was planned and designed,

Usually in our analyses we have many load combinations, on which we would like to consider these P-D effects for all these ones; it could be great to have the possibility to work using many load combinations, something like Staad Pro in which we can consider P-Delta effects in more than 1 load combination.