Product: bryntum/gantt-trial@4.2.4
Is it possible to add sub-task to the first node programatically?
Sure
gantt.taskStore.rootNode.firstChild.appendChild({ name : 'Hello world' })
Docs:
https://bryntum.com/docs/gantt/api/Core/data/Store#function-getById
https://bryntum.com/docs/gantt/api/Core/data/mixin/TreeNode#function-appendChild