  Using the GAMBIT global fitting framework, we constrain the MSSM with an
eV-scale gravitino as the lightest supersymmetric particle, and the six
electroweakinos (neutralinos and charginos) as the only other light new states.
We combine 15 ATLAS and 12 CMS searches at 13\,TeV, along with a large
collection of ATLAS and CMS measurements of Standard Model signatures. This
model, which we refer to as the $\tilde G$-EWMSSM, exhibits quite varied
collider phenomenology due to its many permitted electroweakino production
processes and decay modes. Characteristic $\tilde G$-EWMSSM signal events have
two or more Standard Model bosons and missing energy due to the escaping
gravitinos. While much of the $\tilde G$-EWMSSM parameter space is excluded, we
find several viable parameter regions that predict phenomenologically rich
scenarios with multiple neutralinos and charginos within the kinematic reach of
the LHC during Run 3, or the High Luminosity LHC. In particular, we identify
scenarios with Higgsino-dominated electroweakinos as light as 140 GeV that are
consistent with our combined set of collider searches and measurements. The
full set of $\tilde G$-EWMSSM parameter samples and GAMBIT input files
generated for this work is available via Zenodo.
