I have in the past been able to use my mesh for a Ummu person by changing the UmmUsdk.h for that vessel
const char UmmuMeshUsed[NUMBER_OF_MMU_TYPE][25]={
"ummu/LISUMMU", //passenger
"ummu/LISUMMU", //captain
"ummu/LISUMMU", //"astronaut",
"ummu/LISUMMU", //"security",
"ummu/LISUMMU", //"vip",
"ummu/LISUMMU", //"Scientific",
I know that the LISUMMU is in the right directory Meshs\UmmU
But I can't get the Ummu guy to change.