Hi Kevin,
Yes, you can assign different ranks to a single enclosure. Just treat the extra enclosed rank the same as you would any other enclosed rank and give it the EnclosureCode te same as the others have.
For example the St. Anne's example organ 6 with all frills has the Swell division with the EnclosureCode 220.
So for each rank where is has:
<Encl_IsEnclosed>N</Encl_IsEnclosed>
<Encl_EnclosureCode></Encl_EnclosureCode>
just add that EnclosureCode and it will put that rank within the Enclosure.
I.e. make it:
<Encl_IsEnclosed>Y</Encl_IsEnclosed>
<Encl_EnclosureCode>220</Encl_EnclosureCode>