Hernan S

The easiest way to keep a 1 to 1 hierarchy between Maya and Houdini is doing it through USD nowadays - is pretty straightforward.
Then in Maya, you just convert to Maya meshes if you do not want to deal with USD but you have all the hierarchy in place.

So instead of using FBX, you will export as USD to Houdini from Maya with the same hierarchy, then in LOPS you do the instance, and you have multiple choices on what method to use in the instancer for export this will depend on what you get back from the instances, then use ROP USD to export it back to Maya.

Then in Maya, you load USD into the stage and right-click on the prim/prims that you want to convert back to Maya meshes, done.

Btw - You can always do the same in Maya, do the point instancer, or just instances, etc there, so it really depends on what you need to get from Houdini.

if you are in one of the latest RS versions you can try and use the alembic procedural to render.

You can definitely do everything through MatX and USD in Maya and bring it into Houdini and you should render without any issues in Karma.

If you have Vray materials in Maya then you will Vray in Houdini as well to make it work seamlessly and it will need to be just Vray nodes used but obviously, you won't be able to render with Karma.