GTM - DNS delegation according to manual

im looking at delegated zones for GTM, i first looked at 11.2.1 document BIG-IP Global Traffic Manager: Implementations section Delegating DNS Traffic to Wide IPs. then at Creating a delegated zone on a local DNS server it says:

In order for BIG-IP GTM to manage the web applications of store.siterequest.com and checkout.siterequest.com, you must create a delegated zone on the DNS server that manages www.wip.siterequest.com. Perform the following steps on the selected DNS server.

1) Create an address record (A record) that defines the domain name and IP address of each BIG-IP GTM in your network.
2) Create a nameserver record (NS record) that defines the delegated zone for which BIG-IP GTM is responsible.
3) Create canonical name records (CNAME records) to forward requests for store.siterequest.com and checkout.siterequest.com to the wide IPs store.siterequest.com and checkout.siterequest.com, respectively.

to me it seems this approach can't work. anyone with experience with this agree?

from some testing i think there are two alternatives:

1) create some sort of intermediate NS which you point CNAMES to, so create the gtm.siterequest.com zone and then create CNAMES in the siterequest.com zone

store.siterequest.com --> store.gtm.siterequest.com

checkout.siterequest.com --> checkout.gtm.siterequest.com

2) just create the NS records for the store.siterequest.com and checkout.siterequest.com with the name server being the the GTM and then you can use whatever you want before store / checkout.siterequest.com, i.e. www.store.siterequest.com

but the description from the manual is just wrong in my opinion.

i checked a couple of other versions manuals and so far only the 11.0 makes sense, it uses the intermediate zone approach. the rest want to use the second approach (i guess) but keep mentioning these CNAMES which don't do make sense in that approach.