Ask Mr. Smarty Plants

According to our webpage on Styphnolobium affine (Eve's necklace) should be propagated from seed.

"Propagation

Description: Sow scarified seed after the soil has warmed.
Seed Collection: Collect seeds when the pod begins to dry and the seeds turn red. Separate seeds from pod and store in bags or containers in a cool dry place. Soaking the hard pods in warm water will soften them and make seed removal easier.
Seed Treatment: Seeds must be filed or mechanically scarified with a knife.
Commercially Avail: yes"

Possibly the failure of your attempts at transplanting could be due to the wrong soil or failure to provide good drainage for the new plant. Note also these condition comments from the webpage:

"Conditions Comments: Eves necklace is so named because this tree blooms clustered pink flowers that mature into black, bead-like strings of seeds. The planting site must be well-drained or it will get chlorotic. It grows from seed to 6 ft. in 3 years. This plant is most attractive when grown alone, as it becomes spindly in competition from larger plants. The flowers and seeds ar poisonous."

We could find no further information on whether this plant had joined roots as some thicket-forming plants do. However, note that it is recommended that it be grown alone.

We suggest you read our Step-by-Step Guide on How to Plant a Tree. We would add transplanting a woody plant should be done in colder weather, November through January, if possible. Also, because this plant must have good drainage, add some decomposed granite or sand to the native soil and mix it in. Further addition of compost to the soil will not only assist in drainage but also make the nutrients in the soil more accessible to the new little rootlets.