Consult with Pediatrician physically for further evaluation and treatment

Yes it is contagious and will affect your daughter if stays in contact.

HFMD spreads through respiratory droplets and children are prone more than once. Maintain hand hygiene , frequent washing and make sure your son is well hydrated. Avoid close contact, clean toys which they share.

Yes.its communicable disease.

Can spread Maintain hygiene and make distance between siblings

Yes it is highly contagious and infection once doesn't confer a lifelong protection

Hand, foot, and mouth disease (HFMD) is highly contagious and can still spread to your daughter. She is only immune to the specific strain she had previously, meaning a new strain can cause reinfection. Fortunately, older children usually have stronger defenses and experience much milder symptoms than a two-year-old. To protect her, practice strict handwashing, sanitize shared toys, and prevent the children from sharing utensils. Keep a close watch for signs like a fever or mouth sores, and consult a pediatrician for guidance.