Not a fan of cow's milk or BM in cup

CarlyDW21

I've been putting off weaning DS #2 further because he's not into drinking BM, or cows milk from a cup (and certainly not a bottle). He nurses 3-4 times a day still. He'll drink water no problem from a cup/straw/sippycup, but not milk. We've tried different cups, just a straw in a glass, just a cup like his big bro and he'll have a sip and that's it. Any advice?

TIA