Nicholas,
I tried inserting an external "Add" button in the tool bar and it seem to be working. Try this :
<ej-grid id=....
<e-toolbar-settings show-toolbar="true"
custom-toolbar-items='new List<object>() { new Syncfusion.JavaScript.Models.CustomToolbarItem() {TemplateID = "#AddRecord"} }' <== Add button will appear in toolbar
toolbar-items='@new List<string> {"search", "excelExport", "pdfExport", "wordExport"}' />
...
...
</ej-grid>
Add script with Controller and action to call external view in an anchor tag. you can pass a query string to indicate it is a new. I had used Id as -1 to add a new data..
<script id="AddRecord" type="text/x-jsrender">
<a class="right" rel='nofollow' href="Controller/Action?Id=-1">Add</a>
</script>
