Sep 6, 2021, 02:5009/06/21
Pending an answer from someone else.
I do not know the specific answer to your question, of if ,or how, to do the things you asked.
Sorry if you already knew this, but because of some post I read on the forum, I am pretty sure that solo onslaughts can be performed, however the inference was there's a cut off point in the game when you can no longer do this.
If you can still do solo onslaughts I would suggest you try the usual way and see if it works