How to get the Mesh Index of HISM?

I have a blueprint that places Instances of HISM randomly - a second blueprint that casts to the HISM Component an replaces them during runtime, i can get the transform and the index of the Instance to store them via Array/Struct to keep them to replace them again - the spawner BP can spawn 2 versions of Instances - but if i add them back later it only replaces them with one of them via → get components by class (HISM) → get Array of HISM (0) → add instance.
to change that i would need to read and store the Index of the chosen mesh - but from cast to HISM Component i cant seem to get the index? only transform, name and physics informations but not the Mesh index… how do i get this?

Thanks in advance