sp,
ok i can continue now as my dd just went to bed. let me address your niece's situation 1st, as i think it's rather serious. a MAJOR reason your niece is drinking so much milk and so frequently is because she is GENUINELY hungry. your MIL could be inadvertently starving her you know, that's why your niece has to drink so much milk and so frequently in order to satisfy her hunger. at 10.5mths old, babies MUST be taking 2-3 solid meals a day, and only 3 milk feeds a day. they MUST eat 2-3 solid meals a day because milk ALONE (no matter how much or how often you feed them) WILL NOT satisfy their hunger. aiyoh...doesn't your SIL know what your MIL is doing to her daughter? there could be long-term medical repurcussions here, as your niece could be slowly starving, and may not grow properly as she is NOT getting the proper nourishment that she needs for her age.
ok, you imagine being in her situation. in the morning you wake up and have 1 meal, then for the rest of the day don't eat anything except just drink liquids (be it milk, juice, water, etc) every 1.5-2.5hrs. wouldn't you be hungry too, and then need to keep drinking every 1.5-2.5hrs in order to satisfy that hunger? would you do this to yourself? do you think you would be getting proper nourishment if you just take 1 meal a day and drink milk the rest of the day? if you won't then can you bear it being done to a little baby?
i feel that you also need to do something about this, becuase if you don't then i'm afraid your MIL might end up doing the same thing to your son!
the reason your PD was probably not too concerend about your bb's milk intake at that age is because he should be eating solids already, and so long as he takes 16-20oz of milk per day, he is getting enough. i think if your PD found out that your MIL is refusing to feed your bb solids at this age, then he WILL be concerned, becuase by 6 mths all babies MUST be fed solids already. i doubt any PD would be giving you tips on how to increase your bb's milk intake at 6mths, as usually from this age onwards they will naturally decrease their milk intake.
you know, sometimes these old folks mean well, but they really do not know that some of the things they're doing may be wrong and detrimental to the health of our babies. eg last time our grandmas used to feed our parents diluted condensed milk! they said ok what, bb still survive and grow. but would you feed that to your bb now??
btw, how much milk in total does your bb drink per day, and how many feeds does he get? i seriously think you need to revamp his feeding lah...
if you want to get an idea of what a 6mth old's daily feeding schedule is like, look at this plan from KKH:
http://www.kkh.com.sg/PatientHealthLibrary/ChildrensHealth/FoodnNutrition/Weaning.htm
as you can see, even nutritionists from KKH are recommending that at 6mths old, babies eat 2 solid meals a day, and have 4 milk feeds a day, and that by the time they are 7mths old, they have 3 solid meals a day and 3 milk feeds a day. so you see, the way your MIL is feeding both your bb and your niece is NOT the right way. you need to do something about this, and do it FAST.