Can a 21 years old revert sister lead her 16,17,18 years old brothers who would like to take part in ramadan, prayers and convert to islam in prayers?

Assalamu Alaikum waramatullah wabarakatuh, I am a 21 years old revert sister, from a Christian family recently I noticed my brother and two cousins are interested in my religion, my brother who is 17 has met with me with his intention to fast Ramadan and pray but he doesn't know how to or even know what to say, he says he will pray together with me.. is it permissible if I lead the prayer or if we pray on the same row, I do not understand how to go about it, thank you. Assalam Alaikum.