Javascript excution order

I have the following code.

(1) Page.ClientScript.RegisterStartupScript bring up a dialog box for a new item to another list.

(2) Use loadPerson() to reload the gridview to include the new item created in (1).

However, the dialog box seems popup after the loadPerson() so the new item is not display in the gridview. Is the "ClientScript" always runs at last and if there is any solution?

Many thanks.