Sure, but they were different in origin and mixed later.
I found something very interesting, almost funny about the Unterkrainische Gruppe:
https://www.grin.com/document/347043
Like mentioned earlier, the movement of the culture was from the East, to the West, with first Channelled Ware, then Thraco-Cimmerian horizon, then Basarabi-Hallstatt.
The Unterkrainer just copied the custom of elite burials, without using it for such an elite, because they had none, but rather chiefs of the clans, no higher elites in luxury and princely graves. So they made a huge tumulus, like other Hallstatt groups, but put no-body in the central part, but many members of their clans at the fringes!
This clearly shows that they adopted cultural practises from the then culturally dominant Northern groups, just like the Thraco-Cimmerian horseman gear, but they just copied it superficially, like to "stay in the game", without really taking up all the ideas and societal elements. So they could show other tribes: "We got big tumuli too."
Typically, the more Basarabi-Northern Pannonian, possibly Daco-Thracian related groups preferred cremation, like mentioned before.
The Sulmtal-group was somewhat intermediate between the rather Illyrian Unterkrainische Gruppe and the more North Pannonian-Daco-Thracian influenced and Celtic oriented Fr�g and Kalenderberg groups, but clearly not that much in the Illyrian sphere any more. The Northern Croatian groups too being more Pannonian oriented, rahter than Illyrian.
J2b was found in Novo Mesto, read about it here too:
When the Celts conquered the region and destroyed the Illyrian culture, even the walls being demolished, the Celts started with cremation burials again:
https://www.grin.com/document/347043