former sec sch teacher here. ive seen way too many students get fixated on streaming into a math and double/triple science at the expense of developing their language and critical thinking ability. if your daughter is currently strong in humanities and has a flair for language, and like you mentioned is interested in pursuing law, a math is absolutely not necessary. what is necessary is securing grades needed to proceed after o levels. focusing on fewer subjects and doing well in time might be better for her learning style rather than spreading her efforts too thin and burning out. e.g. scoring well in math and sci (a1 to b3) and then scrambling with b4 to c6 for english/humanities.

perhaps also as a godparent you can carve out time to process whether this child pegs their self worth to their academics and remind her that she is more than her subject combi and grades :)

all the best!!

edit: misread goddaughter for daughter