I was told that my kids can't enter sunday class because we late for registration .my question is Sunday class for all Muslim kids or, its private school?

Salaam Alakem..... I believe That the Sunday school class is a private school situation. But guest students are allowed. You may have been denied because coming late can be a distraction to the Teacher, students and their lesson . However. I can a assure you that guest students are indeed welcome to join and will be treated with the kindest hospitality and Courtesy. In Sha ALLAH. Salaam Alakem

I'm sorry sister I'm afraid that you asked the wrong person. I'm not a member of the community. I just stop and pray there when I happen to be in the area. So I do not know what to tell you. Jazzakallahu khoir may Allah make it easy for your kids to attend the school.