Hi Felipe Bahianana almeida,
Thanks for your interest in Syncfusion products.
Sort summary child rows.
To sort the grid from top level to the bottom level you can make use of the following form link which replicates your inquiry.
If the reported behavior could not be achieved please provide me your essential studio version, and the sample file you have customized. So that I can modify it and provide you.
Please let me know if you have any concerns.