Split tasks - overlapping?

Is it possible to have overlapping split tasks? I want the second phase to begin before the end of the first phase

Hello Ted,
Gantt doesn’t have that feature. You need to manually implement it by using Gantt API and Javascript.
The following examples can help you to start:
https://snippet.dhtmlx.com/5/9ba1b4fe9
https://snippet.dhtmlx.com/5/4f53b734b

That’s perfect, thank you