Ohhh this is a serious concern, mama, TB paru-paru aktif tu kena handle dengan doktor dulu sebelum focus kat weight gain, sebab treatment dia akan affect anak's appetite dan nutrition absorption juga. Kawan-kawan aku yang pernah deal dengan TB, they say doktor mesti monitor the whole picture, bukan just add formula je. Please check with paediatrician or pulmonologist dia dulu, then from there dapat better guidance on which milk suits anak during treatment, some kids need high-calorie options, but kena ensure it works with the TB meds. Sending strength to you and anak, this is a lot to handle!