If my sister got covid 2 weeks ago and now she has rebound covid can she give it again to her kids that also got covid two weeks ago? all had covid 2 weeks ago but the kids are good now. will they get sick again?

Most likely, the kids will be fine. Covid-19 infection is very mild in children. Furthermore, I am not sure what you meant by rebound covid? Was she having symptoms or only tested positive again or both? Take care.

If she is infected, there is a risk of transmission. The risk of transmission is reduced by day 10. The children ave antibodies which will protect against a second infection. A COVID-19 vaccine is still recommended to extend protection. Most likely they will be fine. Watch for signs of shortness of breath and fever.