This subject was one of the very first things I have discussed here when creating contents for HW figures. I use 3DSMAX, and all Autodesk programs can only see Poser/DS body groups as split geometries, which is a very BAD thing. There is no option to make MAX understand how this grouping method works. There is an option to weld to a single mesh, but that will change the OBJ vertex order, which invalidates all morphs and also deletes all grouping information from the model.
Nearly all modeling applications work this way, and there are only a couple that can understand Poser/DS body groups properly. This means I can model with MAX, but I can no longer edit anything once it has been grouped in Poser, and neither I can attempt to group it in MAX because it will split it into several split geometries. That is no fixing to that, and the only way is to use another program.
All this because Poser/DS use groups in a different way than most 3D modeling applications. HW has recommended using Modo because it's one of the few programs that can understand Poser/DS grouping, and they claim it to be the best program to create figure morphs with. For the record, all HW figures were created with Modo. I have started to play with it and it was the first time I have ever imported a Poser mesh into a 3D modeling application without collapsing all groups, or splitting the figure into multiple parts. It was one of those "ah-ha" moments. This is major, because I could never edit contents once they were grouped in Poser or DS, because I couldn't put them back into a single mesh.
All DAZ and HW figures are SINGLE mesh in the original OBJ, but it may be split into multiple parts when exported, or when edited in most programs. I don't know if Blender can understand this kind of grouping, but if it does, you are a very lucky person, because most other programs don't.