How to change unit's model? I'd like Grenadiers to have Volks' model and Jaegers and Stormtroopers to use Grenadier's models instead.To change models, in the ebps category delete the entity_blueprint_ext, copy the same from the entity with the model you want, and paste it to replace the one you deleted.
And one more thing, spawner_ext works for Ostheer buildings (I succesfully added MG34 for them) but doesn't always work for OKW. I managed to add Ostheer mortar crew for Battlegroup HQ but when I try the same with MG42 it simply doesn't show up.
However, the animators for the models don't all support all the weapons, so the replacement may leave your unit holding "air guns". (I have not been able to get the VG model to hold any type of MP-44, which should be a possible upgrade for them.)
For the MG42, in the sbps squad_requirement_ext there is a required_race and required_structure, both of which will keep West German buildings from building it. Right-click on requirement_table and remove all it's contents. (I have done this, for the same reason as you.)
As an aside, you can define a required upgrade that lets you build one before the upgrade, and the other afterward. I use this to toggle between building Grenadiers and Volksgrenadiers.