If you haven't already, you could put each of these sequences
into your phonebook, and "call" each "number" to execute the
diversion.

They will be slow to execute, because the call-forwardings are
passed to the network for processing and storage.  The same
delay would apply to implementing them via "AT" commands.

As far as concatenating two of these into one "number" is
concerned, I understand that's effectively what you've tried
unsuccessfully.  The only thing I would add is to try putting a
couple of pause characters between the two.  The pause
character can be different on different phones (check your
manual).  On some phones, press and hold the asterisk and get a
"p" appearing.  On others, use a plus, "+" for a pause of 3
seconds or so (when within a string - not beginning it).  For
example,

       **21*<divert number>*11#ppp**21*<divert number>*89#

just might be worth a try.

John