You could, but it's easier to do it the PHP code
if ($_SERVER['REQUEST_METHOD']=='POST') {
$stmt1 = $db->prepare("INSERT INTO a_rosters(uniform, nameFirst, nameLast) VALUES (?,?,?)");
$stmt1->bind_param('sss', $uniform, $fname, $lname);
$stmt2 = $con->prepare("INSERT INTO wp_terms(name, slug) VALUES (?,?)");
$stmt2->bind_param('ss', $name, $slug);
foreach ($_POST['uniform'] as $k => $uniform) {
$fname = $_POST['nameFirst'][$k];
$lname = $_POST['nameLast'][$k];
$name = "$fname $lname";
$slug = strtolower("$fname-$lname");
$stmt1->execute();
$stmt2->execute();
}
}
To do it in the query you would
$stmt2 = $con->prepare("INSERT INTO wp_terms(name, slug)
VALUES (concat(?,' ',?), lower(concat(?,'-',?)) );
$stmt2->bind_param('ssss', $name, $slug, $name, $slug);