Simple XML append in BPEL

I am trying to simply append an array of elements to another array in a BPEL process and have tried every permutation of Copy, CopyList and Append on the source array, each node in the source array, the target array, each node in the target array, etc. and nothing seems to work.  Imagine this:

XML schema has a data structured called <Person>, which has child elements like <FirstName> and <LastName>.

A BPEL process has a local variable called $group which is an array (minOccurs=1 maxOccurs=unbounded) of <Person> elements.

The outputVariable for that synchronous BPEL process has a root-level element named <People> which should be an array of <Person> elements.