Hi Daniel,
Thanks for using Syncfusion product.
We have analyzed your query. As of now, we don’t provide support to change the series type in legend by in-build, so we have added it to our feature request list and it will be available in any of our upcoming release.
We have prepared a sample which shows the normal behavior of series type changing. In this we have changed the type of second series. Kindly find the sample from below link.
Thanks,
Dharani.