Possible to get access to DataTextField on Expand?

I could have a very n-deep treeview but the way the dataTextfield operates solves my problem. Is it possible, when the node is expanded, that you modify the array for which the dataTextField is displayed?

 For example:

 When the call is made to the service, the JSON Object return is:

The first node name should be : VBN

so the dataTextField: [SSM.securitySelectionModelName]

 

{"id": 1, "isSSMNameNode": true, "tgtWeight": 0.0, "currWeight": 0.0, "hasChildNode": true, "ext_model_id": 1, "parent": null, "SSM": {"id": 1, "securitySelectionModelName": "VBN"}

 

On the next get, it should be ["SSM.securitySelectionModelName", "SSM.classificationName]"

[{"id": 2, "isSSMNameNode": false, "tgtWeight": 0.0, "currWeight": 0.0, "hasChildNode": true, "ext_model_id": 14, "parent": {"id": 1, "isSSMNameNode": true, "tgtWeight": 0.0, "currWeight": 0.0, "hasChildNode": true, "ext_model_id": 1, "parent": null, "SSM": 1, "classificationNameNode": null}, "SSM": {"id": 1, "securitySelectionModelName": "VBN", "classificationNameNode": {"id": 14, "classificationLevel": 2, "classificationName": "MBS", "hasChildNode": false, "parent": 2}}]

 Is this possible to do on the expand event where I create the dataTextField array dynamically?