You will have to graduallly decrease the frequency from day to only night feeds by increasing more calorie dense food or start introducing milk in glass And night feeds can also be weaned in the same manner . It is a difficult phase for both mother and child emotionally so stay strong , take help from your parents and partner

Consult to Pediatrician physically for further evaluation and treatment

Gradually reduce feeding of older child and start giving him outside food more

For the older child gradually decrease the breastfeeding and introduce outside milk. Better to give milk through cup or glass rather than bottle.