I really hope you get it sorted but (and maybe I am missing something?


) but is it not so that under 3's (at date of arrival) are free of charge for the whole holiday and therefore are also free in restaurants? Hence no need to have half board for them?
If you have already booked buffalos bills separately, are going to inventions (buffet so they are free) then you would have vouchers for one evening left over (the evening when you go to BBWWS) Could you then use the extra kids voucher at Auberge to cover your second child. This would then still leave you with 2 adult vouchers which you can use at face value for lunch on one of your days?
Like I said, i hope you manage to sort it but I don't think it is your TA being difficult as Disney wil not sell half board to under 3. (I actually know people who fibbed about the age of their 2 year olds, saying they were 3, to get the hb vouchers for them when the current offer provided them for free) a