My go to tree for Juvenile and adult Parson’s is the Schefflera specifically Calyptratus Tupidanthus which is multi trunking but there are several types that work great.
Schefflera's species are great for Calumma parsonii ssp. I would recommend Schefflera arboricola for juveniles Calumma parsonii parsonii and Schefflera amate for adult Calumma parsonii parsonii.
I also recommend having a walk around your local nursery for non toxic plants that have got good sized circumfrance stems.