I already had progress. I added on unit prelink button the next script:
~ Si se elige sólo Order Draconis se agrega Battleline como Rol en Batalla
if (tagis[roster.orderdraco] <> 0) then
perform assign[TipoUnidad.Bl]
perform assign[compgroup.tgLineab1K]
endif
It solves part of the problem, but can the stat be changed before the selection?
