Tacx make a stabilizer for a couple of their roller systems. The Eco is one ,not sure of the name of the other model, that attaches to the roller frame thus allowing those of a nervous disposition to be clamped at the front by the Q/R.

I think the idea is to elimanate the fear of balancing , with rear wheel on the twin rollers and the front wheel stabilized until confidence grows sufficiantly to go solo on all 3 rollers