See tutorial: Detect, classify and edit spines (3D)
To combine two spines, use the Merge button.
You can only merge two spines objects at a time (three or more is not possible).
To separate two spines that are modeled as one spine due to physical proximity, use the Split button.
In most cases, the split location is unambiguous and only one split operation is required to obtain the two desired spines. For more complex cases, you may need to perform several Split and Merge operations to obtain a satisfactory model.
Selected spines are displayed with a wireframe.
Appearance settings are displayed.
You can only use the Spines toolbar in the classic window, not in 3D.
Reference: Dickstein, D.L., Dickstein, D.R., Janssen, W.G.M., Hof, P.R., Glaser, J.R., Rodriguez, A., O'Connor, N., Angstman, P., and Tappan, S.J. 2016. Automatic dendritic spine quantification from confocal data with Neurolucida 360. Curr. Protoc. Neurosci. 77:1.27.1-1.27.21. doi: 10.1002/cpns.16
Detect spines (3D), Analyzing spines and synapses with Neurolucida Explorer