SAM & MSRS Combination

Hi, when selecting the MSRS (Multiple Support Response Spectra) assessment option within the Dynamic Analysis settings, the SAM Case (Seismic Anchor Movement) dropdown becomes available as indicated in the following screenshot. What is the purpose of assigning a SAM case to an MSRS case, when considering that a manual user combination is then required, as explained in the follow post?

To illustrate this further by way of example, SAM case S1 could be selected from the dropdown in an MSRS assessment for analysis case 1, but then response case R1 could be manually combined with a separate SAM case (S2 for example).

Kind regards,