Until someone comes along who can help, I had a look at Google. Under
http://www.google.com  I tried felbatol and clicked search and got about 50+
hits back of possible articles.
  When I refined the search to either felbatol&breastmilk  or
felbatol&breastfeeding and got *0 hits on either.   (If you want to do other
searches and want to refine it to more than one item like sentence above,
you can make a search that needs to meet 2 or 3 matches for retrieval, by
putting the & in there as I did in sentence one of this paragraph.)
  If you don't hear or see anything here by Monday that's of help, you
could call your own Pharmacy and ask them if they have either a website or
can give you a printout if you went in.  (My pharmacy here has a Healthwatch
Printout that comes with new Seizure Prescriptions and explains how to use
the ones I use.  It explains potential side effects, and (if applicable)
includes notices either if we should discuss with a Dr. if we plan to become
pregnant (I can't), or plan to have a child or breastfeed, etc.  as per your
request.)
   So if you don't hear or see anything by Monday, there's another source
you could try.  Good luck.  G./

I haven't used this drug, but have you checked this site?
http://www.epilepsy.com/medications/b_felbatol_pregnancy.html

This is a website my epileptologist recommended.

Take care,
Julie