Currently this is not possible with Form Builder: each cell must hold a control which points to different data, and the controls are unrelated.
If you want to hack, however, you can do that, but at your own risk, as Form Builder won't know about your changes.
I put an example here:
- I modified the second
xf:select1
to point to the same bind as the firstxf:select1
- I added an
xxf:group="my-group"
attribute on eachxf:select1