I don't know how to manage dreamweaver per se, but if you are an experienced SQL programmer new to PHP, here are some hints:
You can create forms that will submit an array of values:
<input type=text name=name[]><input type=text name=gender[]><BR>
<input type=text name=name[]><input type=text name=gender[]><BR>
<input type=text name=name[]><input type=text name=gender[]><BR>
Above would create three text inputs on your form.
After the form is submitted you can check the values thus:
$submittedNames=$POST['name'];
$submittedGenders=$POST['gender'];
Then use a for loop or similar. Assume you have created a new family and created a new family id '1234', you could say:
$familyid=1234;
$loopfor=count($submittedNames);
$i=0;
while($i<$loopfor){
$child=$submittedNames[$i];
$gender=$submittedGenders[$i];
mysql_query("INSERT INTO familyOffspring SET id=$familyid, offspring='$child', gender='$gender'");
$i++;
}