I would to know if it is possible to set multiple items as

I would to know if it is possible to set multiple
items as selected at tree initialization and after.

When I try to put select=“1” on each item in the XML file, it
seems to conserve only the last item specified as selected.

You need to enable multiselect feature before loading
xml with multiple selected item

           
mygrid.enableMultiselect(true);

           
mygrid.loadXML(file);