Math in Class 1 CBSE

My daughter is studying in a private cbse school and she is in class 1. During her admission, I paid the school for the books and they gave me the NCERT mathematics book for class 1 along with other books. Later, they said in their WhatsApp group that they are going to teach the class 1 students math from another book named "absolute mathematics 1" from holy faith. After enquiry I was told that ncert math book is lame and that's why they are using another mathematics book which is full of math activities and problems. They said they will teach the students from both the books and summer homework, regular homework and exam questions will include questions from both the books. In other words, they forced the parents to buy 2 books for math subject in class 1. When I complained, they gave me a free soft copy of the holy faith math book. Then after going through the soft copy of the holy faith math book, I learnt that they will be teaching multiplication table from 1 to 10 as well as division to the students this year. When I said teaching division to the class 1 students is a bit too much, and other private cbse schools in my area is teaching only upto table 5 or table 10 of multiplication, they said I am being over-protective and they are doing it according to the ICSE syllabus so that their CBSE students won't fall behind the ICSE students. What I want to know is- 1. Can a private cbse school force the parents to buy 2 books for 1 subject in class 1? 2. Is it ok to teach "division" in class 1, when the ncert math book for class 1 doesn't have this chapter?